RV Utilities: Plumbing & Tanks
RVillage members share their knowledge and helpful tips about RV plumbing, and the various water tanks found in RVs.
Photo credit, top: David (the Gypsy)
RV Plumbing can be mysterious—with all the tanks that need filling and dumping, seemingly miles of Pex piping that runs along the subflooring beneath cabinets; that groaning, vibrating water pump—and the water heater tank that's hidden away someplace unknown! Where do you begin to understand it all?
Self-contained system = tanks
Let's start with the tanks. When you are "dry camping" (either parked overnight in a driveway or lot, or boondocking in the boonies), you will not be hooked up to an external water supply or waste dump. You will be relying on the RV's built-in fresh water and waste water tanks, which is the working definition of "self-contained." This enables you to camp anywhere (that camping is allowed), one of the many benefits of traveling in an RV. You'll need various hoses, fittings and accessories for filling and emptying ("dumping") those tanks.
The fresh water system
Will you drink from the fresh water tank or only use it for showering and doing dishes? If using it for drinking water (or the icemaker), an extra level of water filtration will be necessary. Never use a regular garden hose to fill the tank.
Whether you're filling the tank or hooking to "city water" (more below under "hookups"), you'll need to begin with a fresh water hose that is only used for clean, potable water. This hose is usually white with a blue stripe, or sometimes pale blue. It can be found in RV supply stores, most hardware stores, and Walmart. See LOTS of helpful tips for buying a freshwater hose.
RVillagers recommend: Before hooking a hose to a water spigot—at a campground, RV park, or any place obtaining water from—always do a quick spray of a bleach/water solution on that spigot! (2 tbsp bleach per quart of water)
Next, you will want some filtration to keep sediment and dissolved metals out of your tank. If you're also drinking the water, you will want to also filter out bacteria. There are many in-line and whole-house filter units available. RVillagers discuss the various options here, and more filtration systems here.
The in-line filters should be fitted on the hose when gravity-filling your tank or portable water containers as well.
Where do you fill your fresh water tank?
If you are staying at an RV park, you can top off your tank there. When traveling, there are many options for obtaining "potable" (drinking) water. Here are some helpful recommendations, and more tips here.
Filling the tank from external water containers
If you plan to boondock and don't want to break camp sooner than your 14-day limit, you may want to carry extra water back to the rig. How do you get that water into the main tank? RVillagers offer their suggestions, and more ideas here.
Be sure you are not exceeding the holding capacity of your gray and black waste tanks by adding and using the extra fresh water. Although some BLM land allows for dumping gray water from tanks on the ground, it is not a best practice for the environment—especially with the increase of campers everywhere. It's ok to dump a dishpan of gray water, or take a shower outdoors, but gray water from a holding tank that's been sitting for awhile could be breeding harmful bacteria. You'll know by the odor of that water!
The water pump
When dry camping, you will be relying on the water pump.
Caution: "City water" pressure may be too strong for RV plumbing.
If you prefer to camp with hookups, you will be connected to an external water supply and not be using the internal tank (or the water pump). In addition to a water filter, you will need to add a water pressure regulator—to prevent any excess pressure that the external water source may exert, from bursting your inside pipes. Learn more here.
Getting hooked up: the sequence
RVillagers recommend: Prevent flooding accidents by turning off the outside city water spigot, or the water pump, when leaving your RV for the day! See discussion.
Draining the fresh water tank
There are times when you will need to drain the fresh water tank, like after de-winterizing (more on that topic below).
Depending on the size of your rig, you may have one or two tanks that your sinks and shower(s) drain into. That waste water is known as "gray" water. The gray tank doesn't require a lot of attention, but after many years of use, there may be some sludge build-up—especially from the kitchen sink.
Helpful tip: Wiping dishes with paper towels first will help prevent excess food scraps from getting into your gray tank.
RVillagers recommend: When hooked up in an RV park, do not leave the gray dump valve open. This should be opened only after dumping the back tank to help rinse the waste pipe.
The black water system
The black tank probably gets the most attention of all. Dump station tales involving black water blunders are fodder for many a hilarious campfire story—especially involving newbies—but seasoned RVers are not immune to these mishaps, either.
It's obvious that the toilet drains into this tank, and sometimes one or more sinks as well—this adds more liquid to the black tank to help with drainage, preventing the dreaded "pyramid of poop" (also known as the "pyramid of doom"). If this occurs, however (and it sometimes does!), refer to the next section:
Unclogging a black tank
See helpful suggestions for tackling this unpleasant situation.
Is special RV toilet paper required?
Do you need to spend a small fortune on "RV TP?" Responses vary widely, and some folks don't put any paper into the tank to help prevent clogged pipes. More TP tips here.
Do you need to use chemical additives for the black tank?
Some RV owners swear by them, while others are adamant that they are not necessary for a properly working system. See lots of practical ways to keep your black (and gray) tanks clean and odor-free.
Whether you are camping with hookups, or stopping at dump stations, you will need a special hose to empty the waste tanks. RVers jokingly refer to this is a "stinky slinky."
Where do you store that hose when it is not in use? SO many ideas (with photos).
Stuck black water valve? See some possible solutions.
RVillagers recommend: When hooked up in an RV park, do not leave the black dump valve open, or sewer gases may travel up into your rig.
A macerator pump is another sewerage solution employed by some RVers. Learn more about those in this discussion.
Do they ever really work? Especially for the black tank?
HOW do you dump the waste tanks?
What's the procedure? First-timers need to know!
Here's a helpful pictorial guide. (Note: you may not need all of those steps).
Pro tip: Learn where the valves are for dumping the black and gray tanks (and which is which)—always dump the black tank first, and wear disposable gloves when doing this task.
What's a "blue boy"?
If you've done any long-term boondocking, especially in the winter "snowbird" areas of the southwest, you will see (empty) blue tanks strapped to ladders, and (full) blue tanks with wheels being towed to a nearby dump station.
Using a portable waste tank is another technique used to prevent from having to move the RV to deal with tanks—when parked long-term without hookups. Learn more in this detailed discussion, and check out this thread (with photos of the various brands of blue boys).
Should ALL of your tanks be empty when traveling?
What is the weight of all those liquids?
Did you know? If you have the cab windows open while driving a motorhome, an air vacuum can be formed, pulling odors from the black tank. (The roof vent pipe does not have a strong enough natural draft to overcome this.)
Pro tip: Experienced RVers suggest traveling with your fresh water tank 1/3 full—in case you don't reach your destination that day, so you are not stranded somewhere without water.
The hot water system
The water heater (if not a "tankless" model) typically has a very small tank, 6-10 gallons, usually found under a bed or dinette seat, with the heating fixtures on the adjacent outside wall.
Here's a thread about understanding the flow of water through a hot water tank—with a simple diagram!
Learn more about the different kinds of water heaters in this long, helpful discussion.
See tips for replacing the anode rod inside the tank (if yours has one; propane-only and Atwood water heaters do not).
Related post: RV Propane / water heaters
Sink drains smelling bad?
See some practical tips for odor elimination.
The RV shower
Suggestions for keeping the shower drain clog-free.
Need a tub for the kiddies?
The RV toilet
Flush lever not working? Here's a fix that you can do yourself!
Toilet bowl not holding water?
RVillagers offer helpful advice.
What's that smell?
On-board clothes washer leaking?
Check out this detailed washer valve repair, with annotated photos.
Related post: Doing laundry on the road / onboard washers
RV pipes, connectors, and valves
Learn about RV water flow: pressurized, gravity, setting up valves for control and more. RVillagers share their helpful advice for their own experiences, along with photos.
In-line pipe vents are important in odor management. Learn more in this thread.
- Leaks: finding and fixing. See detailed discussion.
- Trouble-shooting a leak in the hot water system.
- Having issues with the Pex connectors? Find simple solutions here.
- Leaky Pex fitting? Here's how to fix.
Will regular household cleaners harm RV plumbing?
Winterizing the RV plumbing
Do you need to winterize if it's only going to be a temporary freeze?
See responses here.
Winterizing an onboard washer
Join some groups to ask questions, find answers, and offer solutions!
- Why didn't I think of that? Tips and Tricks
- RV Repair Club
- Handy RV Tools and tips
- RV Education 101
- Routine Maintenance
Return to The Guide Chapter: RV Utilities
Disclaimer: The information gathered here is compiled from the posts and opinions of RVillagers, and not of RVillage itself. RVillage assumes no responsibility for any inaccuracies or omissions.
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