Matt Johnson

Understanding RV Plumbing System Basics

Author: Matt JohnsonPhotos/Graphics: Mike HawthornePublished: Mar 28, 2023Updated: Dec 13, 2023

Water is an essential part of camping and road trips, but they can also be intimidating if you don’t know the RV plumbing system basics. Understanding the different components, when to use them, and how to keep them in working order is key to having a great RV experience.

From learning about your water pump’s capabilities, the various RV waste tanks, and winterizing your tanks to sanitizing drinking water for consumption, there are many steps involved in maintaining an RV’s plumbing system. With just a little knowledge and effort, however, you’ll be able to ensure that everything runs smoothly on your next adventure.

Components to your RV’s plumbing system.

Before we start diving into the various aspects of your RV’s plumbing system, it is important to understand the components that make up this particular component of your rig.

  • Faucets. These include your bathroom sink, kitchen sink, and any other places where you might need running water. All faucets in your RV are designed for both hot and cold water, and some may even include a shower option.
  • Shower. Believe it or not, many RVs have more than one shower. Typically there is the main bathroom shower, but there may also be an outdoor shower for rinsing off after a swim or other outdoor activities.
  • Toilet. Every RV has at least one toilet, and many come with two. These drain to your black water holding tank.
  • Pipes. The pipes of your plumbing system connect the two main parts of your system: the freshwater supply and the wastewater disposal. These pipes must be able to withstand extreme temperatures and the pressures of keeping your RV’s water system in working order.
  • Water pump. When you use your freshwater tank (more on that in a minute), you need a way to get the water to your fixtures. That’s where the water pump comes in. The pump is used to move your water from the freshwater tank to the faucets, showers, and toilets.
  • Hot water heater. We all enjoy taking hot showers, and a hot water heater is necessary to make that possible. There are two main types of water heaters used in RVs: gas-powered and electric. Both provide hot water to your RV’s taps and showers. Your RV water heater may also be a hybrid. That means you can select either gas or electric.

The freshwater, gray, and black RV tank.

These components you don’t really see too often because they’re in the belly of your camper. However, they’re some of the more significant parts of your RV plumbing system.

  • Freshwater tank. Your RV fresh water tank is the container that holds the freshwater supply for your RV. It is designed to be self-contained and not connected to any external water source. Sometimes campers call this the potable water tank.
  • Gray water tank. The gray water tank is where all the wastewater from your sinks and shower goes. The gray water tank also has to be self-contained so that it does not contaminate any external sources of water. Most of the time, you’ll have only water and soap in this with little to no solids. Of course, unless you rinse food down your sink. We don’t recommend doing that.
  • Black water tank. The black water tank is where all the wastewater from your toilet goes. It must also be kept sealed and separate from other parts of your RV’s plumbing. Some campers will call this the septic tank or simply the black tank.

That’s it for the components of your RV plumbing system. Now we’re ready to take a look at some of the basics of how it works and how to maintain it.

Where does your RV get water?

Let’s take a look at how your RV or camper gets water in the first place. This seems like a logical place to start.

Your RV will either get water from an external source or it will be stored in the onboard freshwater tank. If you’re hooked up to a campground or other source of potable water, then your water supply will come from there.

City water connection inlet.

If you’re camping at an established campground, state park, or other location, chances are there will be a city water connection available. This is where you plug your RV into the park’s water supply and gain access to running water.

When you connect to a city water supply, this is no different than connecting your home’s hose to your travel trailer.

The city water supply is cold and pressurized. That means you don’t have to use an onboard pump, and you don’t need to worry about water pressure.

Oftentimes the city water provides too much pressure. In that case, you’ll want to put a water pressure regulator on your hose. This will protect the rest of your RV plumbing systems from receiving too high of water pressure.

Don’t worry; they’re cheap and easy to use. I usually keep my water pressure regulator on my RV hose all the time.

Fresh water tank.

If you’re boondocking, dry camping, or camping off the grid, you will need to fill up your freshwater tank and carry your own freshwater supply.

You can fill up your tank at a campground, gas station, or another source of potable water. Make sure you only use water that is safe to drink. RV tanks are typically rectangular in shape and measure between 20-50 gallons.

The onboard freshwater tank will be connected to the rest of the plumbing system and will be the source of your water supply.

Once you have filled up the tank, use an onboard pump to transfer the fresh water from the tank to your fixtures. The pump is essential for providing consistent water pressure throughout your RV’s plumbing system.

Keep that in mind. If you’re using your freshwater tank as opposed to city water, you’ll need a power supply of some sort to power your pump.

Hot water heater essentials: How it works in an RV.

Now that we’ve established how water gets into your RV let’s take a look at the hot water heater.

Your RV hot water heater is responsible for heating up the freshwater coming from your tank or city water and delivering it to your sink and shower fixtures.

If you have a newer RV or camper, there’s a good chance your water heater is both gas and electric. To determine if your water heater has this dual functionality, look for a switch on your wall that allows you to select either gas or electric.

Nonetheless, most water heaters take only a few minutes to heat up. This is because they’re generally smaller. Most of the time, they’re between 5 and 10 gallons. That might not seem like much, but most RV showerheads are water efficient.

Our water heater, for example, is a 6-gallon dual electric and gas. Most of the time it takes about 10 minutes to heat up the entire tank. That will last about two 5-10 minute showers before we need to let it heat up more water.

You might even be able to find RVs with tankless water heaters. They’re not very common, but I think over the next few years, they’ll be more commonplace.

How your RV handles wastewater.

Using all of this water in your sinks, shower, and toilet also means that you need to be mindful of how your RV handles wastewater.

Most RVs have both a black water tank and a gray water tank. These are two separate tanks that handle different types of waste.

Gray water.

Gray water is simply wastewater coming from your sink and shower fixtures. This water is not contaminated with waste, so it’s considered non-hazardous and can be disposed of in most campgrounds and RV parks.

Gray water gets its name from the grayish tinge that comes from washing dishes or taking a shower. This water will collect in the gray water tank and then get emptied out when you need to dispose of it.

Your gray water tank typically holds between 25-50 gallons of water and is located underneath your RV.

Black water.

The other type of wastewater that your RV needs to handle is black water. This water comes from your toilet and contains human waste and other contaminants. As such, it needs to be emptied in a specific location designated for disposing of black water, usually an approved dump station.

Black water tanks are typically around 30-40 gallons in size and also located underneath your RV.

Emptying your black tank and gray tank.

At some point, both of these tanks are going to get full, and you’ll need to empty them. How fast they fill depends on how much you use your RV’s fixtures. It’s a good idea to check your tanks regularly and empty them when they’re about half full or so.

When you do need to empty out your tanks, make sure that you have the appropriate gear first. You’ll need a sewer hose and connector kit in order to connect to the dump station. This will allow you to safely and easily empty out your tanks.

Now you’ll want to locate a dump station. You can usually find these at RV parks, campgrounds, and other designated areas. Once you’ve found one, all you have to do is connect your hose and connector kit, pull your black then gray handles, and then let gravity do the work for you.

A good technique is to drain your black tank first. Once your black tank is completely empty, then drain your gray tank. While both are a form of wastewater, your gray tank water is just soap and water (for the most part). This will essentially rinse your hose out and leave it clean for next time.

Once you’ve emptied your tanks, then make sure to rinse them out with some clean water from your fresh tank or city water. This will help remove any residue or build-up that might have formed in the pipes.

Black Tank in RV

Mastering the art of RV plumbing maintenance.

When it comes to RV plumbing system basics, it’s essential to take some measures to keep your system in tip-top condition. Here are a few tips for making sure your RV’s plumbing is running flawlessly.

Inspect your RV plumbing system regularly.

Check pipes, fittings, and connections for leaks or damage frequently. Keep in mind that some of the pipes, valves, fittings, and tanks may be hidden within walls, so you’ll need to look for signs that there might be a problem.

Take precautionary measures by checking your RV’s plumbing system often for pesky leaks or blockages. Look for signs of corrosion, wear and tear, and other potential problems. If you find any issues, address them immediately to prevent further damage or costly repairs.

Drain and clean the tanks after each use.

Empty freshwater, gray water, and black water tanks whenever they’re full and especially after each camping trip.

Use tank cleaning solutions to keep them clean and smelling fresh.

Many RVers choose to use a tank cleaning wand that attaches directly to your hose and helps break up any residue that may have accumulated in the black tank.

You can purchase an aftermarket san-t-flush kit that helps to flush the black water tank and keep it fresh. This allows you to connect a hose to the outside of your camper and rinse your storage tank as you’re flushing it. Some RVs and travel trailers come with this pre-installed.

Drain all Antifreeze and Flush Tanks to Thoroughly Dewinterize your Travel Trailer

Know where you can safely empty your tanks.

Make sure that you know the proper locations for emptying each tank before setting out on your trip. Many campgrounds and RV parks have designated dump stations. If you must, many single-family homes have a cleanout that can be used to empty your black water tank.

Be mindful of what gets put down the drain or toilet.

Avoid putting anything other than human waste and RV toilet paper in the black water tank, as this can result in clogs or buildup. While RV toilets can handle just about anything (they don’t clog like normal toilets), it’s the black tank you have to worry about. Always use biodegradable toilet paper and never put anything down the drain or toilet that doesn’t belong.

As for your gray water tank, you can put sink filters in your sink basins to keep hair and other debris from getting in your tank. Never pour cooking grease, oil, or chemical products down the drain—these can cause severe damage to your plumbing system.

Winterize your RV before the first freeze.

If you live in an area that experiences cold winters, make sure to winterize your RV before the first freeze occurs. This will protect your pipes from freezing and bursting and prevent any costly damage or repairs.

Each RV and camper is different but generally follows the same principle. You want to remove any trace of water from your pipes, tanks, and water heater. You’ll also want to use antifreeze to protect your RV plumbing system from any remaining water.

Common RV plumbing system questions: We’ve got answers.

Still have some questions? Don’t worry; we’ll answer them for you. We get a lot of questions about RV plumbing systems and these are some of the most common ones.

How do RV plumbing basics differ from residential plumbing?

RV plumbing is designed to be more compact and flexible to fit within the limited space of an RV. The primary difference between RV and residential plumbing is how water supply and wastewater are managed.

RV plumbing has separate tanks for freshwater, grey water (from sinks and showers), and black water (from the toilet). Connecting to a municipal water supply or filling the RV’s water tank provides drinking water, and the wastewater tanks help manage waste generated during your adventures.

It’s essential to properly maintain your RV’s plumbing system to ensure a comfortable and hygienic experience on the road.

What are the different ways to obtain water for an RV?

There are two main ways to get water for your RV: connecting to a municipal water supply or filling up your RV’s fresh water holding tank before heading out. When staying at an RV park, you’ll often have access to a city water supply, allowing you to hook up a hose and enjoy continuous water flow. For more remote stays, you’ll need to rely on your RV’s water tank, which holds a limited supply of drinking water.

Always be prepared and make sure you have enough water to cover your needs while traveling, especially when staying off-grid.

How do I manage wastewater in an RV?

Dealing with wastewater is an essential part of RV plumbing maintenance. An RV has two types of wastewater tanks: a grey tank (for sinks and showers) and a black tank (for toilet waste).

When you’ve filled up these tanks, you need to find an RV dump station where you can safely dispose of the water in your wastewater tank. This process involves connecting a sewer hose from the tanks to the dump station inlet and flushing the contents.

Regularly emptying and cleaning your tanks is crucial to prevent odors, clogs, and potential damage to your RV’s plumbing system.

Can I run my water pump while connected to city water in an RV park?

It’s not recommended to run your water pump when connected to a city water supply at an RV park. The water pressure from the municipal source is usually sufficient to deliver water throughout your RV, and running the pump can cause excessive pressure or even damage the pump. Instead, turn off the water pump when you’re hooked up to city water and only use it when relying on your RV’s water tank for water supply.

Is it okay to drink water directly from an RV’s water tank?

Yes, you can drink water from your RV’s water tank as long as it’s properly maintained and regularly sanitized.

To ensure your tank holds safe drinking water, always use a clean hose when filling it and routinely sanitize it using a solution of water and unscented household bleach. Additionally, consider installing a water filter at the kitchen faucet or using a portable water filter to remove any potential impurities and improve drinking water quality.

What’s the best way to winterize my RV plumbing system?

Winterizing your RV plumbing system is essential to protect it from freezing temperatures and potential damage due to cold weather. The process involves draining all water tanks, removing any remaining water, and adding antifreeze to pipes, fixtures, showerheads, and the water heater.

You’ll also need to clean the water filter and flush the toilet to make sure it’s in working order when you’re ready to hit the road again. It’s best to consult your RV manual for specific instructions related to winterizing your plumbing system.

How does an RV macerator pump work?

An RV macerator pump is used to pump the waste out of the black tank. It’s a powerful tool that allows you to empty your tank without having to find a dump station.

The pump works by grinding up solid wastes and converting them into small particles that can be pumped through a garden hose out of the black tank. This process makes it easier to empty your tanks and keep them clean, reducing odors and ensuring a pleasant RV experience.

Of course, it’s still wastewater, so you’ll need a place to properly dispose of the macerated waste.

When can I use the water pump in my RV?

Your water pump should be used only when you’re relying on your RV’s tank for a water supply. When hooked up to city water at an RV park or campground, turn off the pump and use the municipal source.

The pump is responsible for pushing pressurized water throughout your RV and should only be used when necessary.

How long can I expect an RV water pump to last?

A quality RV water pump should last several years with proper maintenance.

Regularly inspect and clean the filter, as well as check for visible signs of damage or leaks. Additionally, avoid running the pump when it’s not needed and always make sure your tank is filled before turning on the pump.

Be a pro when it comes to your RV water system.

RV water systems can seem intimidating at first, but with a little knowledge and regular maintenance, you’ll be able to keep your RV’s plumbing system in top condition.

It’s important to understand the basics of how it works – from when you should use the pump to how best to winterize your tanks. You also need to make sure that any drinking water is properly sanitized before consumption.

By following these tips and taking good care of your RV’s water system, you can ensure a safe and comfortable experience on the road for years to come.


Matt Johnson

Senior Content Writer

Matt is an experienced camper and glamping enthusiast with a Master's degree in Wildlife Science from Texas A&M University. Authoring posts for GlamperGear, he shares his wealth of knowledge on picturesque campsites, luxurious accommodations, and the best gear for outdoor adventures. His passion for nature and knack for comfort in the wilderness make him an expert guide for your next camping endeavor.

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