RV Plumbing

Your Guide to the Plumbing in Your RV

If you’re like most people, then you probably don’t spend a lot of time thinking about indoor plumbing. The only time when it would cross your mind is if there’s a problem. A backed-up toilet or a leaky faucet are reminders that we use a complex system that was unheard of just 100 years ago.

When living in an RV, however, plumbing becomes a natural part of life. Whereas your home can operate mostly without problems or maintenance, your RV will require constant care and attention.

This was something I wasn’t prepared for when I first started riding around in my rig, but I quickly became accustomed to it. When you’ve had a toilet back up in your RV, you will learn super fast how to avoid that problem from ever happening in the future.

Today I will be teaching you the basics of RV plumbing so that you can avoid my mistakes (as well as any of your own). You don’t have to be a master plumber to know what to do, but you also don’t want to wait until there’s a problem to figure out how to solve it.

Let’s get down and dirty and see what elements of RV plumbing you will encounter.

Water is Precious

Living in a modern society means that we tend to take water for granted. Every time we turn on a tap, the clear liquid comes out, and we have seemingly unlimited access to it wherever we go. However, in an RV, water becomes a precious commodity.

It isn’t until you run out while taking a shower or cooking when you realize just how much you need it to do everyday activities. After the first couple of times draining the tank all the way, I learned how to ration my water usage so that it never happened again.

You too will have to change your mindset when it comes to water. Unlike your home, you won’t be able to waste a drop of it, so you have to learn how valuable it is beforehand. As I mentioned, the first time that you experience a water shortage will be jarring. Thus, it’s imperative that you adjust your usage levels to avoid that problem in the future.

Anatomy of RV Plumbing

Before we dive too deep into the various components that comprise your water system, it’s imperative that we first understand what elements you will come across. One thing to keep in mind is that modern RVs are much better equipped than those from the old days. As such, you may be missing out on advanced technology such as water heaters and updated toilets. Still, this is a pretty accurate list of what to expect in your RV’s plumbing.

  • Water Tanks: there are three of them – Fresh, Black, and Gray. Freshwater is what you refill and what you use the most. Black water is from the toilet, and gray water is everything else (i.e., sinks, shower, etc.).
  • Water Pump: this is the device that delivers water pressure to your plumbing system. Unlike in your home where there’s always water pressure, in an RV, water has to be pressurized to provide what we take for granted at our house or apartment.
  • Drain Valve: there will be one at each tank. Remember that gray and black water have to be dumped according to local regulations.
  • Inlet Valve: most RVs allow you to connect to a water source for continuous plumbing (i.e., a hose connector).
  • Water Heater: you should know what this does already

As you can see, the plumbing system is not too complex. However, that doesn’t mean that you won’t encounter issues from time to time. Let’s break down each section and go over various tips, tricks, and considerations.

Fresh Water Tank

As I mentioned, you can either connect to a water source directly, or you can refill the tank and keep it topped off. In either case, make sure that the water you’re using is potable. Since you will be utilizing it for cooking, drinking, and bathing, it has to be clean and free of any harmful elements, such as bacteria or heavy metals.

I strongly recommend connecting to a water supply as often as possible and using your fresh water tank as a reserve. This will not only ensure that you don’t run out, but it will make your life so much easier when you don’t have to worry about how much you’re using at any given time.

If you are drawing from the tank for extended periods, it helps to estimate how much water you’re using for each activity. For example, running the sink continuously can use up to two gallons per minute (depending on the level of water pressure). Taking a shower can also drain your tank about as fast (or more).

Also consider keeping the fresh water tank safe for drinking. While it might be tempting to use a water filter as you pump city water into the tank, don’t do it. Most water filters are carbon-based and do a great job at eliminating chlorine. You need that chlorine to keep bacteria and other organisms from thriving in your fresh water.

Overall, start timing yourself when using water and measure your tank as often as possible. You should be able to determine more specific numbers based on your RV model, so be sure that you’re accurate in your measurements.

Gray and Black Water Tank

For the most part, the only time you have to worry about these tanks is when you have to empty them. The most vital thing to remember is that you can’t dump your waste anywhere, so be sure to do some research and find spots where you can empty both of them.

When it comes to your black water tank, however, there are some other considerations that you have to keep in mind. Since this receptacle is holding human waste, you have to treat it with proper care and attention.

Don’t drain it too often. If you do, then it will become mostly solid waste, which will start to get funky much faster. Usually, you should do so when it’s at ⅔. Most use gravity to drain the black tank, so you want to have a good amount of “stuff” in it to provide enough force for excavation of the tank.
On the other hand, don’t wait too long to drain it. If you wait until the tank is completely full, that’s going to be a bad idea. Not only do you risk having the water come up through the toilet, but the odor will become unbearable.

  • Rinse it after each dumping. Not only should you use fresh water to rinse the inside of the tank, but you might want to use non-toxic cleaners as well.
  • Wear gloves every time. You will understand why if you don’t.
  • Keep bleach and other cleaners handy. You will want to disinfect the hoses and connectors after dumping.
  • Double check that the fittings are tight. Again, you don’t want to learn from experience.

Water Pump

This handy device is a crucial element in your RV’s plumbing. It’s what delivers water pressure to your various faucets and shower heads, and it’s the only thing keeping your fresh water from filling the pipes when they’re not in use.

Typically, you will have a 12-volt water pump, which is more than enough to get the pressure you need. However, if you have a larger RV with a lot more water requirements, you may have a more powerful motor.

One thing that I recommend is to install a basic water filter on the outlet side of your fresh water tank. This will keep debris and other materials from getting in and clogging the pump. Although that shouldn’t be an issue, it’s always a good idea to plan for the worst.

When looking at your pump, make sure to check its ratings regarding how much pressure it can deliver as well as how long it can run without overheating. For example, when taking a shower you will be using the pump the whole time, so don’t overload the system.


Your RV will be equipped with a variety of valves that can control where water enters and exits. It’s imperative that you check and maintain these valves on a regular basis. Also, it’s essential that you know when to shut them off and turn them on. For example, if you’re not using the inlet valve, it should always be closed. This will prevent water from leaking out, and it will maintain proper pressure in the lines.

In some cases, you may have valves that connect to a particular part of the RV, such as the sink. These valves can come in handy since it will allow you to disconnect the pipes and faucet without having to drain the tank.

Overall, learn where they all are and be sure to label them if necessary. You don’t want to close the wrong valve by accident.

Water Heater

If your RV comes equipped with a water heater, then you have to pay attention to both its power requirements as well as whether it holds water or just heats it as it passes through. Since it requires a lot of energy to heat water, I recommend using it only when running the generator or plugging into an outlet. Otherwise, your batteries could get drained in minutes. If it runs on gas, these are usually very efficient and you can reasonably run the water heater for an extended period of time.

Other Tips and Tricks

Here are a few other considerations to remember when using and maintaining your RV plumbing.

  • Use a Pressure Regulator: when drawing from a city water spigot, you have to be sure that the pressure is not going to overload your system. As such, it’s a good idea to install a pressure regulator that will equalize everything automatically. Refer to your motorhome manual and it should specify the city water inlet pressure range.
  • Shut Everything Off When Not in Use: for example, if you’re parking your RV, turn the water system off so that it won’t cause problems.
  • Drain Your Tanks Before Storing Your RV: once you’ve returned from your trip, empty all of the tanks and wash them out. You don’t want to come back to your vehicle and discover a nasty odor inside.
  • If You’re Not Sure, Don’t Use It: this refers to fresh water only. If you don’t know 100% that it’s potable, don’t risk it.


Thanks for reading! I hope that you found this information useful and that it will help you on your next RV adventure. Once you get the hang of your plumbing, you will realize that it doesn’t take much time or effort to keep everything in tip-top shape. Just don’t get complacent and always remember to check your tank levels whenever possible.

Happy RVing!