Welcome to the fun with liquids page! The information here is mostly
based on my own personal experience. Working with plumbing is pretty straightforward
and usually isn't terribly dangerous, unless you gouge yourself with a
screwdriver or drop a wrench on your foot. However, improperly installed
or poorly repaired plumbing can lead to your RV filling with water (or
other far more disgusting substances!) so it's important to do the job
right the first time. Some of the suggested RV modifications require you
to be at least a little handy... Don't undertake any project beyond your
One of the best things about an RV is it's ability to provide all the
comforts of home even when you are miles away from civilization. Key to
our comfort are simple things like running water and indoor toilet facilities.
Any tent camper can tell you how much fun it is to make a 1/4 mile trek
to the outhouse at 3 am in a pouring rain, or detail the joys of washing
dishes at a spigot. Lucky for us, our modern RVs are equipped with complete
miniaturized equivalents of the household plumbing that we all take for
granted. Even small RVs have partial or complete self-containment capabilities
and the basic design of the plumbing systems are pretty much the same,
from a pop up camper all the way up to a big class A motorhome. Let's take
a look at a simple block diagram:
See... there's not really all that much to it after all! A couple of notes:
there is a one way valve built into the city water inlet and the water
pump has a one way valve built into it.. the valves are shown here separately
for clarity. Some rigs have separate sewer connections for the black and
gray tanks and a few rigs even have 2 different gray water tanks, but the
basic system is still the same... Occasionally, a RV manufacturer will
short cut good design principals and plumb the bathroom sink into the black
water tank, just because it's easier. Luckily, few rigs are plumbed in
this incorrect manner... More on that later.
Getting water into your RV
Don't open a roof vent in the rain! There are easier ways!
The easiest is to simply connect a garden hose between the nearest potable
water faucet and the city water inlet on the side of your rig. This provides
you with water at pressure to all the fixtures in your rig. There are a
few important points to note, however!
Taking your water along for the ride. If you won't be having
the convenience of a fresh water spigot at your destination, then you'll
have to take water with you using your rig's fresh water holding tank.
Filling the tank is as easy as hooking your fresh water hose to a nearby
faucet and running water into the water tank fill opening on your rig.
These fresh water fills come in many shapes and sizes.... here's a typical
First of all, you will like the taste and smell of your water a lot more
if you use a hose designed for drinking water, rather than just any green
It's a good idea to have several lengths of hose, as you never know how
far away that faucet will be. I have a 10 foot, a 20 foot and a 50 foot
fresh water hose and use whichever one or combination of several that reach
the faucet the best.
NEVER NEVER NEVER use your fresh water hose for any other purpose! Don't
use it to wash the car, or (God forbid!) to flush out your holding tanks!
That hose needs to be treated carefully and kept as sanitary as possible.
After all, you're DRINKING this water, right?
RV plumbing was designed to operate at pressures of 40 to 60 psi and most
can tolerate pressures up to about 100 psi. Unfortunately, unregulated
city water can have pressures as high as 150 psi or more. The best bet
here is to always install a pressure regulator on the line coming to your
city water connection. There are inexpensive pressure regulators that simply
screw onto one end of your fresh water hose and they are cheap and effective
Click for a bigger picture.
Click for a bigger picture.
Make sure that the tank drain valve, if there is one, is closed before
starting to fill the tank. If your tank has a vent valve, it's best to
open it to allow the tank to fill faster. If your tank glugs, chuffs and
spits water back at you when filling, then it's likely that it has no vent
or the vent is plugged or shut off somewhere. Simply slow down and let
the tank fill at it's own rate. You can make the task easier by using a
little fill adapter like this... it fits on the end of the hose and then
slips down into the filler. A handy little device to have.
Click for a bigger picture.
Another really handy device to have is a water stealer. These little homemade
items allow you to hook up a hose to a faucet that has no hose threads.
These little devices will allow you to fill your fresh water tank from
just about any spigot or sink tap that you will find anywhere. They are
cheap and easy to make and will save you a lot of headaches somewhere down
the road! To use, just force the end of the appropriately sized stealer
over the non-threaded spigot and secure with the worm gear clamp. Attach
your hose and you're in business. Note: these are for temporary hookups
for filling a water tank and really aren't designed to have pressure on
them for long periods of time. Probably not a good idea to use as a permanent
Click for a bigger picture.
To make a set of your own water stealers, just hit the local hardware store
and buy short sections of 3/8", 1/2" and 5/8" I.D. clear vinyl thick walled
tubing and the male garden hose ends to match the hose sizes. A little
work with pliers and screwdriver and you'll have your own set of stealers!
Once the tank is full, or as full as you want it, shut off the water
and stow your hose and stuff. Don't forget to secure the fill cap and close
any vents if you have them before heading down the road.
Getting water to the fixtures
We're in hot water now!
If you are hooked up to a fresh water faucet, then there ain't much to
it! Hook up the hose to your city water inlet, turn on the faucet and open
a faucet inside the rig to allow any air to escape. It's a good idea to
purge all the sink and tub fixtures and to make sure that the water heater
If you are in a boondock or dry camping situation, you must rely on the
12V water pump in your rig to supply water under pressure to the fixtures.
To get started, open a cold water faucet in the rig and turn on the pump.
Having a faucet open will help the pump prime quickly. When the water is
flowing nicely, close the faucet. Briefly open each faucet throughout the
rig to purge out any air. Once this is done, the pump should stop running
after you close the last faucet and shouldn't run again until you open
a faucet somewhere. The pump is designed to pump the system up to about
40-50 psi and then a pressure sensing switch mounted on the pump shuts
the pump off until the pressure drops. You are all set... just remember
that your supply of fresh water is limited and conserve it! When the tank
runs out, you will hear the pump speed up and the flow of water from the
fixtures will slow or stop. It's best to turn the pump off at this point
until you refill the fresh water tank. These pumps can run dry for an extended
time without damage, but it's a waste of power to just let it continue
to run, so be sure to turn the pump off when the tank runs dry.
Unlike the water heater in your house which requires little or no user
intervention, operating the typical RV water heater requires you to pay
attention to a couple of things...
Where does it go from here
First and most important, before lighting the water heater gas pilot or
turning on any electric heating function, make SURE that the water heater
tank is filled with water!!! Check to be sure that the water heater inlet
and outlet lines are not bypassed with a winterization bypass kit and that
water flows from the hot faucet in the sink or shower.
Once you're sure, go ahead and turn on the heater. Some heaters utilize
an electric heating element in addition to the standard gas burner. Some
heaters require a pilot and some are Direct Spark ignition. Check the manual
that came with your RV or the data plate on the water heater itself for
proper lighting and operating instructions.
Most RV water heaters allow some adjustment of the water temperature. Gas
models will have a temperature adjustment right on the gas valve. Gas/Electric
units will also have a separate thermostat for the electric side, but locations
and accessibility will vary. Best to consult the manual unless you like
to play detective... Be careful not to set the temperature too high...
it's easy to get severely scalded by water heated beyond 140 degrees.
It is not uncommon to see some weepage from the pressure relief valve on
the outside of the water heater when initially heating a tank of cold water.
This is caused by the expansion of the heated water and indicates very
high pressure within the water system. You can open a faucet briefly to
relieve the pressure, but the best permanent fix for this problem (in my
opinion) is to add a small expansion tank to your water system. The expansion
tank will absorb the pressure fluctuations and smooth the water flow in
your rig. See the Enhancements section for more info.
If you have a water heater that utilizes a pilot light, you may be amazed
to find that the pilot will heat your water nicely all by itself. Just
light the pilot and leave the gas valve in the 'pilot' position when you
park and overnight the water will heat up and be ready for your shower
in the morning. This doesn't work well in high usage situations, but can
be a real propane saver for the frugal RVer!
In a non-mobile house, once the water disappears down the drain, we
can forget about it. Not so in a RV.... Every drop winds up in the holding
tanks and then we must at some point deal with it again. Let's look at
that block diagram again.... the waste waters from the sinks and shower
are transported to the Gray Water tank through a series of pipes. Each
drain has a standard plumbing trap that keeps the sewer odors from coming
back up through the drain. The gray water builds up in the tank until we
dump it. Similarly, the toilet dumps directly to the black water tank through
a foot or lever operated valve. This valve seals off the tank when the
toilet is not being flushed and keeps the odors in the tank where they
In most cases, the black and gray tanks are sized slightly smaller than
the fresh water tank... usually somewhere between 20 and 50 gallons each,
although truly large rigs may have tanks approaching 100 gallons each.
The best source of capacities information for your particular rig is either
the owner's manual or the dealer. It's handy to know the actual capacities
of your plumbing system because water weighs! It's safe to figure about
8 lb. per Gallon for water and waste liquids and you can see how it can
add up in a hurry! A 50 gallon fresh water tank, when filled, is going
to add 400 lb. to the weight of your rig. Traveling with full holding tanks
can add a lot of weight and easily put your rig over it's safe operating
weight. Be aware of your rig's dry weight by weighing it fully loaded,
but without fresh water or propane onboard and with empty holding tanks.
Compare this weight to the unit's GVWR.
GVWR - (dry weight) = available capacity for water and propane
Propane weighs about 5 lb. per Gallon.... Be careful not to overload
your rig and always be aware that water has weight and must be considered
as part of your payload!
Many RVers have discovered that when dry camping or boondocking, the
gray water tank tends to fill up pretty quick while the black water tank
rarely ever fills up. This makes sense, as the only source of fluids for
the black tank is the very efficient RV toilet. The gray water tank has
to contain the liquids from all the sinks and the shower. Strangely enough,
however, most RVs have black and gray tanks that are the same size! Given
the above, it seems like a lot of tank capacity is going to waste here
and I decided to do something about it. I designed and installed a simple
transfer pump that will move gray water from the gray water tank to the
black water tank. Details on the transfer pump are included below in the
Occasionally, a RV manufacturer will ignore good design engineering
and plumb the bathroom sink and/or even the shower into the black water
tank, just because it's easier and cheaper. Beware this setup! It makes
it possible to overflow your black water tank by running water in a sink
or shower that common sense says is connected to the gray water tank. If
your black water tank seems to fill up awfully fast, you might just be
the lucky owner of one of these mis-plumbed rigs. If you suspect non-standard
plumbing in your rig, the best way to check is to be at a full hookup site.
Dump both tanks. Close the black tank dump valve and leave the gray tank
dump valve open. Run water into all sinks and shower for several minutes
and monitor the black water tank level. If water shows up in the black
tank, then you have one or more sink drains plumbed to it. This doesn't
mean that you must immediately sell your RV and buy another... it just
means that you are now aware of a potentially annoying and destructive
"feature" and you should keep a close eye on the level in your black tank.
In most correctly plumbed rigs, when you completely fill up the gray water
tank, the drain water will begin to back up into the bathtub or shower,
which is usually the lowest point in the gray water system. This is pretty
harmless.... after all, it's just soapy water and it's not going to hurt
anything. However, if a sink or shower is plumbed into the black tank and
it becomes completely full, then what backs up isn't going to be soapy
water! Plus, it may not back up into such an innocuous place as the tub.
Thankfully, this kind of problem seems to be pretty rare, so your rig is
most likely correctly plumbed.
Most folks agree that the gray water tank can be dumped anytime, no
matter how full or empty, and when you are hooked up to a sewer connection,
the gray water dump valve can be left open at all times. This allows the
water from your sinks and shower to flow directly out of the rig and into
the campground sewer system. Hey, that's easy! However, it is not a good
idea to treat your black tank the same way. Black water contains a lot
of ... well... call them 'solids'. RV toilets flush with very little fresh
water, so these 'solids' are quite concentrated. If you were to leave the
black water dump valve open while hooked to a sewer connection, these
solids tend to build up in your tank and then dry into a disgusting form
of concrete. Over time, a black tank can become partially or completely
blocked, leading to a highly nasty cleaning job or complete tank replacement.
To avoid this, always keep the black water tank dump valve shut. Let the
black water build up until the tank is at least 1/4 full and then dump
it, rinsing with lots of fresh water. Waiting to dump the tank keeps all
those 'solids' in suspension and the quick rush of fluid out of the tank
when it is dumped helps carry most of the solids out. Whenever it's convenient,
try to dump the black tank after traveling... the motion of the rig on
the road will mix up the contents nicely and help break down the 'solids'.
When parked for an extended period, I usually dump the black tank every
couple of weeks if the weather is cool and more often when it's hot. (helps
keep the odors down!) The day before I plan to dump the black tank, I shut
the gray tank dump valve. This allows some gray water to build up in the
tank... then, when I dump the black tank, I follow it with the gray tank
to flush out the hose and help carry the whole mess down the sewer pipe
to wherever it ultimately ends up.
Don't put this stuff down your drains!
Grease or oil. It will congeal in the tanks and pipes and require dynamite
Caustic cleaners or solvents. Tanks are ABS plastic and solvents can destroy
Flammable liquids. Duh!!!
Toxic wastes. More Duh!!!
Food scraps. Even small scraps can build up in your tanks... consider a
drain screen! Click here for an
Don't flush anything down the toilet unless you've eaten it first!! No
tampax, paper towel, bottle caps, toys, Q-tips, cotton balls, etc, etc,
or you'll be SORRY!
Don't use that quilted 3 ply toilet tissue you love.... Sorry! It's best
to use either an inexpensive one or two ply tissue you can get at your
local food store or stick to RV toilet paper. Both work about the same,
but the RV stuff is about 4X the cost! Whatever you use, it needs to disolve
fully in your tank. If in doubt, always do the jar test: take a sheet or
2 of your TP, put it in a jar 1/2 full of water and give it a shake. Safe
TP will dissolve readily, bad stuff won't and shouldn't be used in your
Toilet chemicals containing formaldehyde or any other crap that ends in
"dehyde". Don't use this stuff! It plays havoc with sewage treatment plants
and septic systems alike. Don't believe the B.S. about it being biodegradable....
it's doom and is one of the reasons that so many public dump stations have
Pine oil. Favorite ingredient of home-brew tank treatments, it will do
long term damage to the seals on the tank gate valves, leading to expensive
and disgusting repairs down the road.
I'm really gonna step WAAYYY out on that proverbial
limb and talk about a very controversial subject. What to put down your
toilet to help control 'Odors'. The reason that this is such a scary
topic is that absolutely everyone has a favorite toilet chemical. They
are also certain that the inferior substitute you are using is nowhere
near as cheap, effective, safe or easy to use as their favorite. OK, I'm
joking... a little.... If you ever want to start a lively discussion around
a campfire, ask what your neighbors are using for their toilet!
Personally, until recently, I rarely put any kind
of chemical in my black water tank. I simply dumped my tanks more often
when it was hot to avoid serious odor problems. In the winter, when cold
weather reduced the odors anyway, I never bothered with chemicals at all.
Most of the commercially available chemicals are bad for the environment,
tough on sewer treatment plants, expensive and only marginally effective
at best. I figured that it was 'Money down the drain" and just didn't use
any of it.
Nowadays there are a number of enzyme and bacterial
tank treatments on the market. These products are designed to stimulate
aerobic bacterial action and break down the waste and kill the odors...
kind of like having a miniature sewage treatment plant onboard. They carry
an added benefit in being completely biodegradable and highly beneficial
to RV park septic tanks and sewer treatment plants as well.
If you decide to stick with old fashioned toilet
chemicals, please use them sparingly and avoid using any product with Formaldehyde
as the active ingredient. Most home brew toilet treatments should be viewed
with a skeptical eye. Don't even consider using a home-brew remedy that
has pine oil or Pine Sol in it. Pine oils will harden the seals on the
dump valves and eventually cause leaks.
All RVs come equipped with some sort of monitor system that is supposed
to tell you how much 'whatever' is in your tanks. These systems haven't
changed significantly in the last 30 years and most still rely on physical
conductive probes inside the tanks. Here is a simplified diagram to show
you how this is all supposed to work.
For the most part, this system works pretty good for the fresh water tank
and the gray water tank, but leaves something to be desired for the black
tank. Most folks find that after a year or two, the sensors in the black
water tank stop working. This is due to the probes getting coated with
yuck in the tank and this yuck interferes with the accuracy of the monitor.
There are literally dozens of expensive tank cleaning concoctions on the
shelves of your local RV store and there are almost as many home-brew cleaning
ideas out there... some work better than others, but nothing will fix the
problem permanently. My favorite home-brew tip is to put a few gallons
of clean water and a small amount of dish soap in your freshly dumped black
water tank and then add a large bag of ice cubes. Drive the rig for a few
hours, then dump when you arrive at your destination. The idea is that
the ice cubes will scrub the insides of the tank and then melt. It's worth
a try if your monitor panel isn't working right...
When it comes to the standard monitor systems installed in most RVs,
they are just likely to be inaccurate in use. You can either put up with
it, do a regular cleaning of the tank probes and hope that it helps, or
invest in a replacement tank monitoring system. There are a couple of different
ones out there on the market and they work without any probes inside the
tank. One popular system uses capacitance and simply requires a couple
of sensors be placed on the outside of the tank body. My black water tank
monitor never worked, even with repeated cleaning, so I just ignored it.
When the gray water tank monitor started to act up, I decided it was time
for a better answer. I purchased and installed a system called Acu-gage
and I have been very pleased with it.. It is amazingly accurate and linear
and has worked flawlessly for more than a year. Click
here for more information
Dealing with dumping
Probably one of the least enjoyable tasks associated with RVing is
getting rid of the waste water that accumulates. It's really not so unpleasant,
if you do it right.
Water quality issues / Filters
First of all, buy good quality hoses and fittings.... the heavy
duty sewer hoses cost a little more but will last a lot longer and are
more resistant to springing leaks. It's a good idea to have both a 10 foot
and a 20 foot sewer hose. Equip each hose with the correct fitting to attach
it to your rig's dump connection. It is also a good idea to have at least
one set of sewer adapters to connect your sewer hose to the sewer fitting
in a RV park. I use the red E-Z couplers and really like them, as they
simply screw into the sewer hose, needing no additional clamps. They provide
a neat leak proof connection to the park's sewer system and are quite inexpensive.
There are a number of other brands on the market as well... just pick out
whichever one you like. The unused pieces can be stored in large Ziploc
bags in a compartment. The flanges are removable and the elbows are designed
to stay on the hose and fit either into your bumper stowage or in a custom
sewer hose storage.
At the dump station or sewer connection, park the rig close enough
for your dump hose to reach. Connect the hose to the rig first, then place
the other end into the sewer opening in the ground. If it doesn't want
to stay put, you can place a small rock or brick against it to hold it
in place. A piece of wood or a leveling block can also be used. We don't
want that end of the hose to jump out when we start to dump, now do we....
As a last resort, you can ask your spouse to hold onto it, but this is
probably the least desirable solution, especially if anything goes wrong!
Pull the Black Water tank dump valve first. This way, you will dump
the black water through the hose first, then follow it with the gray water
to flush out the hose. Once the black water tank is empty, you should rinse
out the tank with clean water. This can be done by dragging a garden hose
into the bathroom and running water down the toilet, or you can use a special
flushing stick through the toilet dump valve. Another possibility is to
step on the small pedal to fill the toilet bowel full and then quickly
flush the toilet. Do this a few times and it will rinse out the black tank
to a small extent... If all this sounds like a hassle, (and it is!) check
out the installable tank flushers in the Enhancements section below.
Once the black tank is empty and flushed out, close the black water
dump valve. Now, open the gray water dump valve. As the gray water runs
through the hose, you can shake it around a bit to help rinse out the inside
of the hose, but be careful not to shake too hard and dislodge the hose
from either the rig or the dump. Once the gray tank is empty, shut the
valve and wait a few moments before disconnecting the hose from the rig.
Disconnect the rig side first and lift the hose up so that any residual
water drains into the dump fitting. Now's the time to rinse out the sewer
hose if you like, using a water hose. DO NOT use your Fresh water hose
to do this!!! Most dump stations have a water faucet nearby and sometimes
even a hose, but it's a good idea to have a short section of hose of your
own and only use that hose for rinsing when dumping.
Put all the caps back on. Cap off the dump connection on your rig
and replace whatever cover or plug that belongs with the park sewer connection
or dump station connection. Shake out your sewer hose and stow it and it's
adapters. Make sure that you rinse away any spilled waste or mess, especially
at a public dump station and stow your rinsing hose and close all compartments.
OK, you're ready to go! ... Now, that wasn't so bad, was it? Oh... It's
a great idea to wash your hands at this point.... Some folks like to use
disposable plastic gloves... they put them on before starting and then
just discard them afterwards. I keep a small bottle of liquid soap right
in the same compartment where the hoses and stuff are stowed... makes it
real quick and easy!
Traveling around the country, you will find that the taste and purity
of the available water changes as much as the scenery. There are a lot
of things that we can do to improve the taste and safety of the water we
put into our rig. Let's talk about the safe water issues first.
Safe water means water that won't make you sick. Safe water is water
that doesn't have excessive bacteria, cysts, viruses, chemicals,
heavy metals or other health threatening substances dissolved in it. The
easiest way to protect yourself from these nasties is to only use water
from an approved city water supply or well. This isn't a guarantee, but
it does improve your chances of getting water that won't kill you. Chlorinated
water is safest and usually won't have infectious bacteria or organic yuck
in it, but you are at the mercy of the water supplier when it comes to
other contaminants. Thankfully, most of the water you encounter in your
travels won't kill you or even make you sick but you can improve your odds
by remembering a few simple tips:
Only hook your hose up to a potable water source. Watch out for faucets
at dump stations and heed warning signs.
Use only drinking water safe hoses to supply water to your rig.
Never use your drinking water hose for any other purpose.
Stow the drinking water hose empty and connect the ends together to keep
Don't drag the end of your drinking water hose on the ground.
Always let the water run for a bit at the spigot before connecting up.
Sanitize your fresh water tank at the start of the season and drain it
if it will be unused for more than 2 weeks. To sanitize the tank and the
fresh water system, follow your RV manufacturers instructions or do the
If in doubt about the quality of the water going into your fresh water
tank, add a small amount of common household bleach to the water in the
tank. A teaspoonful of bleach per 20 gallons of water is plenty!
If you are really worried, buy bottled water and use it for drinking and
Prepare a chlorine solution using one gallon of water and 1/4 cup of Clorox
or Purex household bleach (5% sodium hypochlorite solution). Pour
one gallon of solution into tank for 15 gallons of tank capacity.
Complete filling of tank with fresh water. Turn on the pump. Open
each faucet and let it run until all air has been released from the pipes
and entire fresh water system is filled. You should be able to smell chlorine
strongly at each faucet.
Allow to stand for three hours.
Drain and flush the tank and system with potable fresh water.
To remove any excessive chlorine taste or odor which might remain, prepare
a solution of one quart vinegar to five gallons water and allow this solution
to remain in tank overnight or longer.
Drain tank and again flush with potable water.
You can really improve the taste and enhance the safety of your
drinking water by installing an under-the-counter water filter. Many rigs
already have them and they may be plumbed into the cold side of the kitchen
faucet or have a separate faucet for filtered water. My rig was originally
plumbed with an ADC filter that dispensed through the cold side of the
sink faucet. I replumbed it so that it had it's own little faucet. This
filter system is one of the better ones, as it removes cysts and bacteria
as well as bad tastes and odors. The cartridges last about a year with
normal use and the whole system is available from any RV supply catalog
or parts store.
Click for a bigger picture.
Click for a bigger picture.
There are also excellent filters available that attach right to the
water hose outside the rig. These filters come in a disposable type and
a replaceable cartridge type and are fairly reasonable in price. The only
problem is that they don't seem to last as long as a dedicated under sink
filter. Part of the reason is that the under sink filter only filters drinking
water... these units on the hose filter ALL the water going into the rig.
If the water is really nasty where you are parked, it can be real handy
to have both the under counter filter and one of these hose filters so
you can do a 'double whammy' on the water before you drink it. This double
filtration will make even the most icky water semi-palatable.
Click for a bigger picture.
For the ultimate in filtration, a Reverse Osmosis system can be
purchased. Although these systems produce excellent water, they have some
drawbacks when used in RVs and may not be for you. They are quite expensive
and take up a lot more space than a filter. They require a fair amount
of water pressure to work and also create a certain amount of 'waste' water.
Some systems produce a gallon or two of waste water for every gallon of
filtered water! In a home, that's not a problem, as the waste water goes
down the drain. In a RV, where both the supply of water and the holding
tank capacities can be limited, this can make the R.O. system unusable.
If you always have a water and sewer hookup, then it's no problem... but
if you like to boondock, you should probably steer clear of this type of
system. Too bad, as the R.O. systems remove practically everything
from the water.
When I'm traveling, every time I stay somewhere that has tasty water,
I fill a few gallon water bottles and stash them. Then, when I stop somewhere
that has icky water, I just use my gallons of good water for drinking and
cooking. It seems to work out pretty well for me.....
Most older RV fresh water systems are plumbed using gray polybutylene
tubing. Most connections are made using barbed connectors made of either
gray plastic-like materials or brass and either aluminum or copper crimp
rings. This plumbing will resemble the picture below. There have been a
lot of claims that polybutylene plumbing breaks down and eventually leaks,
usually at the connections. I spent some time researching these claims
and I'm sad to say that there appears to be a pretty good case against
the gray stuff. One thing is certain: they aren't making it anymore! It
has been universally replaced by cross-linked polyethylene tubing in most
newer RVs. Identified by it's white or red color, PEX is assumed to be
safe and reliable. The connections are made either with Qest fittings or
the familiar crimp rings as seen below.
Click for a bigger picture.
While scientific evidence is scarce, it is believed that oxidants in
the public water supplies, such as chlorine, react with the polybutylene
piping and acetyl fittings causing them to scale and flake and become brittle.
Micro fractures result, and the basic structural integrity of the system
is reduced. Thus, the system becomes weak and may fail without warning
causing damage to the building structure and personal property. It is believed
that other factors may also contribute to the failure of polybutylene systems,
such as improper installation, but it is virtually impossible to detect
installation problems throughout an entire system. In most cases it takes
years for polybutylene systems to fail. While it may leak within a few
years of installation, the majority of leaks start to occur in the 10-15
year time frame.
Throughout the 1980's lawsuits were filed complaining of allegedly defective
manufacturing and defective installation causing hundreds of millions of
dollars in damages. Although the manufacturers have never admitted that
poly is defective, they have agreed to fund the Class Action settlement
with an initial and minimum amount of $950 million. Homeowners with houses
that were plumbed with polybutylene are eligible to receive payment to
replumb their homes.... unfortunately, RVs of all types were specifically
excluded from the class action lawsuit settlements. The following is excerpted
from the class action settlement documentation:
A "Unit" is any real property or structure situated in the United
States with PB Plumbing installed between January 1, 1978 and July 31,
1995. A "Type I Unit" is a single-family residence, and each part of a
commercial or other structure occupied by a single tenant or tenant group.
A "Type II Unit" means a mobile home (exclusive of recreational vehicles,
boats and travel trailers).
Well, now that I've ruined your day, where do we go from here? One good
point is that the gray stuff seems to be pretty reliable in the low water
pressure environment of an RV. The other good point is that, unlike the
plumbing found in houses, the plumbing in RVs is a lot more accessible.
Repairs on your polybutylene piping should be done by replacing the old
gray stuff with the newer PEX tubing. Qest fittings and the old style brass
crimp fittings appear to be compatible with both types of tubing.
Here's an example of some of the many shapes and connectors you might
see when looking at your RV plumbing. Don't be alarmed by all the variety...
it all breaks down into a couple of sets of hardware, depending on the
inner diameter of the tubing. Any good RV parts place will have a selection
of PEX tubing, fittings, the crimp rings and often even a crimping tool
that you can borrow or rent. This stuff is easier to work with than you
These are some typical barbed connectors and fittings. To add a fitting
such as a tee to an existing run of poly tubing, simply drain the tubing,
cut it using a knife, saw or special tubing cutter and clean up the cut
ends, removing any plastic fuzz. Then, place a copper or aluminum ring
over each end of the cut tubing and then simply push the tubing onto the
barbed fitting. Once it's fully seated, slide the crimp ring up to the
end of the cut tubing and apply the crimp tool to create a finished connection.
If all that sounds like too much work, then you are in luck! There are
a number of different repair fittings available for the poly tubing that
work on the compression principle. One of the brand names is QEST and these
fittings are also available at most RV parts shops and through most RV
parts catalogs. To use these fittings, simply cut the tubing, assemble
the fitting according to the package directions and tighten the compression
nuts. These fittings are substantially more expensive than the more simple
barb and ring ones, but are very convenient and easy to use.
Most faucets used in modern RVs are similar to those used in standard
housing and many share the same parts. You can find washers and repair
parts for most RV faucets and fixtures if you simply take the defective
part with you to the local plumbing shop. The low pressure lines used to
supply water from your fresh water tank to the water pump are common vinyl
tubing, available at most hardware stores. The waste plumbing is standard
household black ABS fittings with very few exceptions. Sink drains, traps,
connectors and drain pipes are all standard sizes and types. Replacement
parts are available at most hardware stores and the piping is usually joined
using ABS plastic pipe cement and standard fittings. The only departure
from standard plumbing parts are RV specific items like dump gate valves
and sewer hose connector fittings and some of the external drain valves
and fittings. The bottom line is that RV plumbing is easy to repair and
modify. If you have basic plumbing skills, you should have no problems
with your RV plumbing. For those of you without basic plumbing skills,
the good news is that RV plumbing is pretty reliable and it's unlikely
that you will experience many problems. The most important thing to remember
is to protect your RV plumbing from freezing temperatures, and we'll discuss
that in the Winterizing section below.
Being a born tinkerer, I made a number of changes and enhancements
to the basic plumbing in my RV. Some of these modifications are presented
here and it's up to you to decide if they might be useful to you. If you
install any of these mods, please be careful to do a good quality job and
test each new fitting under pressure, watching for any signs of leakage.
It's a good idea to keep an eye on any new fittings for a couple of days
until you are sure that they are secure and leak free.
Some rigs come equipped with a sprayer for the toilet from the factory.
Mine didn't, so I added a standard sink sprayer and teed it off of the
water supply line to the toilet. While I was down there, I also added a
shut off valve to the supply line. This sprayer is useful to rinse down
the inside of the bowl after use and will help to break up any... umm...
well, when I was in the Navy, we called them skidmarks... you get
the idea. :-) The third photo shows an awfully dusty shot of
the connections for the sprayer.. looks like I need to clean back there
a little more often! Parts needed were a barbed shutoff valve, a barbed
tee with the correct size threaded fitting for the sprayer connection,
the sprayer, a broom bracket to hold the sprayer head and the necessary
Click for a bigger picture.
Click for a bigger picture.
Click for a bigger picture.
Built in regulator
After leaving my external water pressure regulator behind for the second
time, I decided to eliminate the problem by installing a Shur Flo regulated
city water inlet. This is a great little device and is easy to add to your
rig. It regulates the incoming water pressure to a safe 45-50 psi and since
it's attached to the rig, it's harder to leave behind. An added benefit;
this regulator seems to flow more water than the little brass ones that
you attach to the water spigot. For those of you who would rather have
an external regulator, they also make one set up with hose connectors.
If you are unhappy with the low flow rates you are getting through your
current regulator, this would be a good replacement for you. Available
from most RV parts stores through the Shur Flo catalog.
This is a very useful item and will make your life a lot easier.
It's a tank flushing system that installs permanently into the side of
your holding tank and provides an external hose connection so that you
can easily flush your holding tank. No more dragging a hose inside to flush
your black water tank! I installed one in both my gray and black water
tank and I absolutely love them! The instructions are very good and the
installation is easy enough for even the moderately handy person to do.
Basically, you will need to cut a small hole in the side of the holding
tank and attach the flusher head using the provided screws and some silicon
sealant. Then the simple hose extension is run to a convenient spot under
the rig and provides the hookup point for your garden hose. Inexpensive
and a real hassle saver! These flushers can be purchased from most RV stores
and camping catalogs.
Click for a bigger picture.
Water heater bypass
If you are in the habit of winterizing your RV
with RV antifreeze, this little addition will save you gallons of the pink
stuff! Some RVs have these installed from the factory, but for those of
you who don't have one, several different brands are available. What this
does is allow you to completely bypass the water heater so that when you
fill your water system with RV safe antifreeze, you don't have to fill
the whole water heater as well. The picture shown is a factory installed
setup.... but it gives you an idea of how it works. To bypass the water
heater, drain it and then close the valves on the heater inlet and outlet
and open the bypass valve. Check your RV catalog.... most units are simple
to install and don't require cutting any existing plumbing and simply screw
onto the existing water heater nipples. One note... if you don't use antifreeze
to winterize your rig, then there really isn't any reason to install a
Click for a bigger picture.
This is a mighty handy little item! It's a simple pressure gauge installed
inside the rig to monitor water pressure in your fresh water system. It's
very simple to do... just purchase a standard gauge that will read from
0 to 100 psi or more and add a tee anywhere in the freshwater plumbing.
I added mine right next to the water heater. If you are in the habit of
not using a regulator, this gauge is a real necessity. To protect your
RV plumbing, you should never expose it to water pressures in excess of
100 psi and actually, you are much safer limiting the pressure to 45-55
Click for a bigger picture.
Gray water transfer pump
Here's one that's a little more involved... I noticed early on that
when dry camping, my gray water tank filled up in a few days, but
my black water tank would hardly be at 1/4 full. This seemed like a waste
of tank space to me, so I devised a pump setup to allow me to transfer
gray water from my full gray tank to my relatively empty black tank. This
is a great way to extend your stay, especially when you have a water hookup,
but no sewer connection! If you are interested, Click
here for more info.
This is a do it yourself version of the commercially available expansion
tank setup for your RV. An expansion tank helps smooth the water flow in
your RV and also allows for the expansion of water in your water
heater. If your water heater relief valve leaks or your faucets drip when
your water heater is operating, then this is one for you! An added benefit
is that it reduces pump cycling when operating on internal water. It's
a cheap and easy installation and you can Click
here for more info.
Click here for a Block Diagram showing all
enhancements and their installation.
Possibly the most important thing you can do to ensure the long life
of your RV plumbing is to properly winterize your rig. For those of you
who live in climates where it never drops below freezing, my congratulations!
You can skip this section! Many of us, however, will be storing a rig in
freezing temperatures during the winter months. It is critical that you
take the proper precautions to protect your plumbing from freezing, or
you will be faced with some nasty surprises come springtime.
To prepare your rig for winter storage:
Drain all tanks. Flush out the black water and gray water tanks and be
sure to get them as empty as possible.
Drain water heater.
Drain fresh water system using low point drains if provided. Open all faucets
and step on the toilet pedal as well. Get as much water out of the system
Now, you have a choice... you can either protect your fresh water
piping by using a non-toxic RV approved antifreeze or you can use air pressure
to blow out the remaining water in your water lines. Both methods have
advantages and disadvantages. Using RV antifreeze is probably the surest
method to absolutely guarantee that no pipes will freeze. Properly used,
it will protect your rig well down into sub-zero temperatures. It does
require a lot of flushing in the spring to get the taste out and also makes
it desirable to install a water heater bypass to reduce the quantity of
antifreeze used. Plus, the stuff ain't cheap.
NEVER use any antifreeze or substance in your fresh water system unless
that product is specifically labeled as non-toxic and safe for use in drinking
water systems. Use only antifreeze designed specifically for RV water systems!
In order to easily pump the antifreeze throughout your
water system, you can install a neat little valve that allows your pump
to draw antifreeze directly from the bottle. It's available from most any
RV parts source.
Click for a bigger picture.
Alternately, you can remove the existing hose from the inlet side of
your water pump and attach a short piece of hose to reach into the antifreeze
bottle. Bypass the water heater if you can. If you have an ADC filter
under the sink, install the manufacturer's antifreeze diverter. If you
have a cartridge type filter, remove the filter element and replace the
cartridge holder. Run the pump and open each fixture, allowing it to flow
until you see pure antifreeze. Monitor the level in the antifreeze bottle
and make sure it doesn't run dry. Remember to flush the toilet and operate
the toilet sprayer if installed. Don't forget the shower head. Depending
on the size and complexity of your plumbing system, you will probably need
1-3 gallons of antifreeze. If you don't have a water heater bypass, better
add 6 or 10 gallons to that, depending on the size of your water heater!
Once you have done each and every fixture in the rig, you should have full
protection against freezing pipes in your freshwater system.
Instead of using antifreeze, you can use air pressure from a compressor
to blow the water out of your fresh water lines. This method is cheaper
than the antifreeze method and you won't have to flush the antifreeze taste
out of your water system come spring. On the down side, however, it is
extremely hard to get every last bit of water out of the lines and if sufficient
water collects in a low point or valve, then it may be damaged by freezing.
Plus, there are portions of the water system that blowing the lines won't
clear and you must drain them manually. Still, many people prefer to use
air to clear the lines, rather than deal with the antifreeze. To start
with, you will need a little plug that will fit into your city water inlet
and provide a fitting to connect the air compressor to. It looks like this:
Click for a bigger picture.
Hook up your air source and set it for a max. of 60 psi. Once pressure
is applied, go through the rig, starting with fixtures closest to the inlet
and open them briefly, allowing the air pressure to blow the water out.
Remember to flush the toilet and operate the toilet sprayer if installed.
Don't forget the shower head. Once you have done each and every fixture
in the rig, you should have most of the water out of your freshwater system.
Remove the air source. Now, it will be necessary to remove the outlet line
and inlet line from your fresh water pump and drain them manually, as the
check valve in the pump prevents the air from clearing these lines. Remove
any cartridge from any under sink filter and make sure the fixture is drained.
Your freshwater system should now be in good shape for the winter storage
Now, you need to pay attention to the other plumbing systems in the
Pour a small amount of RV antifreeze down each drain to protect the trap.
Additional antifreeze can be poured down a sink to help keep any residual
water in the gray tank from freezing.
Pour a small amount of antifreeze into the black tank through the open
toilet flush valve.
Close the toilet flush valve and pour a dab into the toilet.
If you installed a gray water transfer pump or any other optional plumbing
system, be sure that they are fully drained or protected with RV antifreeze.
There are a lot more steps to winterizing your rig.... we just covered
the ones relating to plumbing. Best source of additional winterizing info
is your RV owner's manual or RV dealer.
When the summer season gets ready to start, make sure that anything
you disconnected is reconnected and that all hoses and water lines are
visually intact and in good condition. Close any open drain valves. If
you used antifreeze, flush it out according to the antifreeze manufacturer's
instructions. Now is a good time to sanitize your fresh water tank and
system. Replace water filter cartridges with new ones. Refill the water
heater. Apply pressure to the fresh water system and thoroughly inspect
all plumbing connections and fixtures for leaks. If you did everything
right at the start of the storage season, then your rig should be ready
That's It! A veritable flood of RV plumbing information!
Did we get all your questions answered and concerns addressed? If you feel
that I missed something, please drop me a line!
I hope the above info helps you 'stop the drip' and keep all your RV plumbing
leak free and functional!
This page last updated on February 15, 2003
© 2003 Mark S. Nemeth