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Having running water is one of the many benefits of camping in a motorhome. With an RV water tank, you have the ability to rinse vegetables, boil a pot of water, shower and flush the toilet – all from the comfort of your camper. If you’ve never traveled in a motorhome before, you might think getting water is as easy as opening a faucet.

As important as the topic is, it also often leads to questions, problems, and difficulties. In this article, we want to deal comprehensively with the subject of water supply in the motorhome.

Why actually water in RV?

Hardcore tent campers and car travelers often can’t understand why the water in the RV is so important. Even with pure campsite vacationers and camping dealers, we have regular discussions about why 5 gal water on the road is not enough for us. But the motorhome water supply makes the camper for us only “home on the road”.

  • Water for washing hands in the camper

Water is what you use to wash your hands. Why is this important? Well, an RV is not just a vehicle. It’s also a home. And in your home, you want to be able to spontaneously take something out of the refrigerator and eat it. Before I eat something with my hands, I wash my hands. At home as well as on the road. But at the same time, a motorhome is also a vehicle, it needs to be refueled with diesel, the wastewater tap needs to be opened, the toilet cassette needs to be emptied – these are all activities that do not take place cleanly. It’s just nice to be able to quickly wash your hands afterward.

  • Water for cooking in the RV

Pasta, rice, stews, and so on: without water, many ingredients cook rather poorly. And: Yes. We actually often cook in places where water is not available. Therefore, the water in the camper must be there for this purpose.

  • Water for washing dishes

After cooking in the motorhome, it is important to get the dirty dishes clean again. For this, of course, water is also necessary for the motorhome.

  • Water for flushing the toilet

The motorhome toilet also usually needs water for flushing, otherwise, it will not work.

  • Water for showering in the RV

Many do not shower in the motorhome – we do. First, we do not always spend the night at the campsite, but then also do not want to smell ten meters against the wind. Secondly, a shower after sports or when it’s cold outside is simply pleasant. Modern motorhomes allow all the comforts with their wet cell, and even a hot shower thanks to the hot water boiler of the motorhome heater. Showering in a motorhome is a real water guzzler, and this water must also come from somewhere.

  • Water for the outdoor shower

The outdoor shower is a special case, only a few motorhomes have one. The outside shower is not only about being able to shower outside the vehicle, but also to be able to shower off dirty mountain bikes and pets before they get back into the motorhome.

  • Drinking water in the RV

Water is important to us humans, so you would think that drinking water in the RV would deserve the top spot on this listing. But whether you really want to use your water from the water tank in the motor home for drinking water, you should decide only after reading this article. Personally, we don’t: For us, the water tank ensures the basic water supply in the motorhome, but on the road, we use bottled water as drinking water.

Relate: Water tank in the RV: What you need to know

guide water in RV

How does the water system in the RV

The water system in the motorhome is actually always quite similar in design. Also, the operation of the water installation hardly differs from motorhome to motorhome.

To be supplied with water on the road, the vast majority of camping vehicles have a built-in water tank. This freshwater tank in the motorhome is filled (usually from the outside) by hose or canister, so that water can be drawn from it afterward. For this purpose, pipes and lines are laid in the camper. These lines run from the camper water tank, for example:

  • to water taps
  • to the shower
  • to the hot water boiler
  • to the toilet flush

The used water is collected in a wastewater tank and later emptied. So there are

  • A freshwater tank (mostly for 21-31 gal for “normal-sized” RVs, but also several hundred liters for large liners or expedition motorhomes are possible)
  • A wastewater tank, where the used water ends up
  • A pump that transports the water from the freshwater tank to the fittings
  • Faucets/taps for the camper kitchen and wet room
  • A hose line system between these components

How to use the freshwater system in the RV

The intended use of the freshwater system is actually quite simple:

  • Freshwater is filled into the freshwater tank through a filler neck (usually on the outside of the RV). For this purpose, one uses a water hose or a canister.
  • The freshwater can then be used in the motorhome – for washing hands, showering, flushing the toilet, and, if necessary, for cooking and drinking. In the latter use case, water quality is of course very important.
  • The used water runs into the wastewater tank. This collects it so that a controlled emptying at designated places (for example disposal stations, campsites, …) can take place. For this purpose, there is usually a drain valve under the motorhome.
  • Between trips, when the RV is not used, for water exchange and in winter, the freshwater tank should be emptied. There is usually a special valve for this as well.

Water withdrawal by faucet (or shower/WC flush) is made possible by a pump (submersible pump in the tank or pressurized water pump). This means no water without electricity.

Water for toilet flushing in RV

In most cases, the water from the water tank in the RV is also used for toilet flushing. Again, (when using a submersible pump) the pump only runs when the button on the toilet is pressed. To prevent the water in the water tank from becoming contaminated, a check valve is used.

Freshwater pump in the RV: Submersible pump

The pump is usually designed as a simple submersible pump. It is activated by microswitches in the water taps and then, when supplied with electricity, pumps water from the freshwater tank. In the process, pressure builds up in the piping system. This pressure escapes when a faucet is opened, and water comes out of the faucet. When the faucet is closed again, and thus the microswitch disconnects the submersible pump from the power supply again, the water flow stops.

Residual pressure may still be present in the system. If the pump is switched off immediately after the water has been drawn off, water will still come out of the valve for a while when it is opened.

The important thing about the submersible pump is that it must never run dry. If a submersible pump is operated without water , then it overheats and is defective.

Tip: It is recommended to always carry a replacement for the submersible pump in the motorhome. Once you are used to the water system of the motorhome, it is a real shock when it suddenly stops working.

Tip: Most electric control panels in the RV have a separate switch for the water pump. This allows you to deactivate the pump to prevent it from running dry when the water tank is empty, for example. This is also important when winterizing, as the water taps are left in the open position. To avoid having to winterize the rest of the motorhome in the dark, simply turn off the power to the water pump.

Freshwater pump in the RV: pressure water pump

In contrast to this, there are also pressure water pumps in larger and classier motorhomes. With these, pressure is built up in advance (even before the water is needed) by the pump in a pressure vessel.

  • Advantage: By this pressure, the water runs immediately, if one opens a tap, without possibly flowing pump noise.
    In addition, many pressure pumps can run dry, so they are not immediately broken if you accidentally run them without water. This doesn’t seem to apply to all pumps, though, so look it up under your model name!
  • The disadvantage of this solution: Since the system is always under pressure, water damage due to leaking fittings or hoses is much more serious than with the submersible pump (which does not pump water as long as it is not running).

Relate: Best RV Water Pumps 2021 – Buyer’s Guide

Problems with water in the RV

And that brings us to the possible problems with water in the RV. We all know the destructive power of water from cave visits, reports of storms and floods. Water can also cause major damage to a motorhome. But a leaking water system in the motorhome is not the only danger. One does not always know the origin and the purity of the refueled water so exactly. Microorganisms thus get into the water tank. Even the use of a dirty hose can cause high germ contamination of the water. Water can even be “colonized” via the air.

Germs, bacteria, microorganisms

Germs are always found in water, but normally the concentration is so low that we don’t mind. Long periods of standing in the water tank of the motor home can cause germs to multiply, especially at high temperatures. We also know this from pools, for example, which can “tip” very quickly in the summer if the water is not treated.

Mud and sand in the water tank

Water filled up from dubious sources can contain sand, soil, and other particles. These build up in the RV’s water tank and can clog hoses and fittings. Regular cleaning is recommended.


Algae actually require nutrients and light to grow, so they shouldn’t really be a problem in the RV water tank. However, according to reports, they do occur.


Fortunately, less common in our latitudes are viruses in the water. But travelers who take an expedition RV to tropical regions also need to protect themselves from viruses.

When the wastewater tank in the RV stinks

It is not uncommon for the wastewater tank to develop strong odors, especially in the summer. Heat and bacterial cultures in the wastewater tank are an unpleasant combination, and the wastewater tank in the motor home can then really stink. You can prevent this by flushing as little food residue as possible into the wastewater tank of the motor home. Starchy liquids such as pasta water also seem to be very bad.

From our point of view, odor prevention only works to a limited extent. After buying our brand-new van we were really careful, and still we had unpleasant odors already in the second season.

You can find out how to clean the wastewater tank in the chapter on the wastewater tank. What really helps against odor from the wastewater tank is a siphon at the drain. Unfortunately, many motorhomes do not come with this as standard equipment.

Relate: How to Clean RV Fresh Water Tank

water in motorhome

RV: water leaks?

Water leaking from the camper? This can have several reasons and is not always cause panic.

  • Perhaps the water tank is simply full, and therefore allows excess water to escape. By the way, this also happens via the overflow valve on winding roads.
  • Maybe you just forgot to close the drain valve of the wastewater tank?
  • Finally, it could be that the frost monitor is not closed. By the way, this happens automatically at temperatures close to zero. Suction action can then drain water from the tank when the water heater is already empty.

If this is not the case, you must first determine where the water is coming from. Leaky hose connectors or defective fittings after frost damage are the usual suspects here. It is also worth checking (and possibly greasing) the seals of the water tank caps.
If you can’t find the problem yourself, or if you can’t fix it, you should visit your workshop immediately, because water damage is one of the worst things that can happen to an RV owner.

Water damage in the RV

As important as water is to us, its power is equally destructive. Unnoticed water leaks can cause water to penetrate the floor slab, softening it and causing a total economic loss of the mobile home. It does not always come so badly, but also warped boxes and lost vacation time one would like to avoid. Even just not being able to use water can be very annoying on vacation. Therefore, it is important to check the tightness of the water system regularly. Even seemingly harmless defects (like a leaking hose clamp) can result in expensive defects if not noticed right away.

Important: If a fitting or hose is damaged due to water damage, you must repair that damage before you can use water in your RV again. This is because the pressure generated by the pump is present throughout the system. If your kitchen faucet is dripping, it will drip even if you actually only want to use the faucet in the wet room.

Undesirable components of the drinking water in the mobile home

Depending on the origin of the water in the mobile home, it may contain the following substances:

  • Microorganisms include bacteria, protozoa, and viruses.
  • Suspended solids (for example, sludge)
  • Chemicals (for example, pesticide residues)
  • Salts
  • Metals

Hazardous germs include:

  • Enterococci
  • E.Coli bacteria
  • Pseudomonads
  • Legionella

These germs can cause diseases such as diarrhea, pneumonia, and the like.
Water is considered suitable for drinking if it is free of pathogens that can directly cause illness. So this mainly refers to the microorganisms mentioned. The other substances may not be desirable either, but they usually make people sick only if they are present in high doses for long periods of time, which is why they can usually be neglected.

Water conservation and water disinfection

In the RV, water conservation tries to prevent further germination, and water disinfection tries to render existing microorganisms harmless. Viruses can only be killed by heat, UV light, and chemical additives, or particularly fine filters because they are much smaller than bacteria. For bacteria, fungi, and algae, a number of other methods are also suitable. In addition, it can also be useful to filter suspended solids and dirt from the water, because even if they do not directly cause illness, a sludge floor in the water tank is not a pretty sight.

Relate: RV Chemical Toilets: What you need to know

The water tank in the RV

To be able to provide fresh water in the motorhome, the vast majority of RVs have a built-in water tank.
The RV water tank is usually a container made of plastic, which is installed in the vehicle behind panels. Motorhome manufacturers often make water tanks to fit exactly, so that, for example, the hollows of the wheel housings are utilized.

This freshwater tank is filled (usually from the outside) by a hose or canister so that water can then be drawn from it. For this purpose, pipes and lines are laid in the camper. In the water tank is an electrically operated submersible pump (alternatively: pressure water pump), which allows the water withdrawal by tap (or shower/toilet flush). This means no water without electricity.

The freshwater tank of the RV supplies water to taps, showers, and the hot water boiler. It also often supplies water to flush the toilet (though some RV toilets have their own small tank). In addition to the freshwater tank in the motorhome, there is also a wastewater tank.

Tips for filling up with water in the RV

When filling up with water in your RV, there are a few tips you should keep in mind.

  • Water that stands in pipes can be contaminated with germs. It is recommended to run fresh water through the system for a minute before actually refueling the tank. A tank flush can also be useful, especially after long periods of idling.
  • In water hoses used for refueling, the water may have been standing for a long time, or the hose may even have been exposed to the sun: good conditions for bacterial growth. Personally, I always let some water run through there, too, before I fill it into the camper water tank. (I’m sensitive about this, and even do it this way in my own kitchen before I fill my drinking glass).
  • I would not want to fill the RV water tank with the hose next to most supply/disposal stations. Some colleagues, unfortunately, have no idea about hygiene and put the hose into the cassette toilet for cleaning. The next one puts the same hose into his water filler neck. We have observed this several times, and now no longer use hoses near disposal stations.
  • Fill the water tank in the motorhome and not have to stop? But beware: If you don’t use the right adapter here, and make the adapter completely tight, you risk the wastewater tank bursting in the worst case.


✅ Should you travel with water in your RV?

If you are, and there’s no water close to your boon docking location, you may have no choice but to travel with the water on board. On the other hand, if you’re headed for an RV resort with full hookups or a campground with a “known” good water supply, you can skate in and fill up (or hook up) on arrival.

✅ How do you use water in an RV?

Locate your camper’s fresh water drinking hose. If you’ll be using a water filter or water pressure regulator, attach them to the hose now. Screw the loose end of your hose into the campground’s water supply hookup. Set your RV water system to connect to city water instead of your own RV water tank.

✅ How much water should you carry in an RV?

How many gallons of water does an RV usually hold? An average freshwater tank holds 20-100 gallons of fresh water. A class A RV will hold the most water, averaging between 75-100 gallons. Class C RVs will hold 35-60 gallons, Class Bs will hold around 20-40, and fifth-wheel trailers hold about 60-80 gallons.

How does an RV Water System Work - Video

Max Welder (rvneeded)

Max Welder (rvneeded)

Max Welder is a mechanic enthusiast. Currently, working at a small company. Experienced in electronics, car tools, and security systems. In his spare time, he writes articles for various blogs.

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