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How Does an RV Water System Work?

Water – it’s the stuff of life, as they say. But getting water in your RV is a little more complicated than turning on the tap like at home. And chances are you’ve heard some nightmare story about a tank dump gone wrong. In this article, we’re covering the major components of an RV water system and how they all work. Let’s get started!

What Is an RV Water System? 

Your RV water system has specific elements for water intake, storage, filtration, heating, and disposal. Sound complicated? The whole system can be broken down into three main sections – how you get your water (your fresh water intake), how you use your water (your plumbing system), and what you do with your waste water when you’re done (your storage and dumping system.)

Excited RV Faucet

RV Freshwater System Explained

Given that there are critical differences between your RV’s water system and your home’s water system, let’s go over the most notable variances. 

City Water

The easiest way to get a similar experience to your at-home water is by hooking up your RV to what’s known as “city water.” This is what all pressurized exterior water sources are referred to, whether you’re using a campground hookup or a residential faucet. Your rig will have a city water port somewhere on the exterior where you’ll hook up your hose connection. 

Use a hose designed for drinking water – not just any old one from the garden! It’s also important to use a water pressure regulator between your city water source and your RV water system to prevent potentially serious damage to your rig from overly pressurized water. 

Using city water bypasses your RV’s fresh water tank and delivers water straight from your faucets and other fixtures. This method is only available at RV parks, campgrounds, homes, or other places with a reliable pressurized water source you can tap into.

Freshwater Holding Tank

For all the other times, you’ll be using your RV’s fresh water holding tank. These vary in size, but most will allow at least a few days of dry camping or “boondocking” before you’ll need to refill. 

Before heading out to camp at sites without water, fill your tanks with as much as you’ll need for the trip. Keep in mind the impact the additional water will have on your rig’s overall weight. It’s also important to keep this tank clean, sanitizing it once or twice a year.

Water Pump

Without the pressure provided by city water, you’ll need to use your water pump to get the water from your holding tank to your fixtures. 

You’ll generally have a switch to control this pump located near the other controls for your RV’s systems. In some cases, you’ll be able to switch the pump on, and it will automatically kick on when needed. In others, you’ll need to turn it on and off manually.

Water Filters

Most RVers will use at least one water filter for their RV water system. This makes sense, as frequent travelers may not be 100% confident about their water hookup quality. 

You can often find these filters on the rig’s exterior where the city water source enters the water system. They come in several different filtering styles, including sediment-based, carbon, or ceramic. 

rv water filter

These filters play a crucial role in removing bad tastes, odors, and contaminants. They also protect your RV water system and pump from small particles that could harm their operation. Additional filters can also be placed on your faucet or you could use jug-style filters, like Brita pitchers.

RV Water Heater

What good is your RV shower or sink without hot water? That’s where your rig’s water heater comes into play. The water heater is also likely controlled by a switch in your rig. RV water heaters run on either propane gas, electric, or a hybrid of both. 

But don’t expect hot showers like at home, generally speaking. RV water heaters are often maligned as not being able to provide enough hot water for those who like long showers. And with an average capacity of 10 gallons or less, that’s not surprising. 

truma water heater on RV
Our Truma AquaGo On-Demand Tankless Water Heater

Newer tankless RV water heaters aim to solve this by heating your water throughout your RV water system. However, these are generally more expensive and, in some cases, harder to maintain.

We personally use (and LOVE!) the Truma AquaGo On-Demand Tankless Water Heater.

RV Water System Plumbing Explained

Now, let’s look at how your water gets from your RV hookup to every water-based system in your rig. 


Your kitchen water system is centered on your sink. Your sink draws water from your fresh water tank or city water stream. As mentioned earlier, many RVers will also add a filter to their sink or filter their sink water once more in a Brita or other type of portable filter. 

Water that goes down the kitchen sink is “grey water.” This water is dirty with food scraps, soap, and anything else that runs down your sink. We recommend using drain screens to prevent anything too big from making it down there.


Your bathroom water system is essentially two systems – one for the shower and one for the toilet. Both draw from the same fresh water source, be it your tank or city water. Like your kitchen sink, your shower releases grey water, full of dirt, body oil, soaps, and shampoos. 

On the other hand, your toilet creates “black water” – water contaminated with human waste and toilet paper. RV water systems require you to use special types of toilet paper to prevent clogged tanks.

Grey Tank 

The grey tank is where your grey water is. Grey water isn’t quite raw sewage, but you should still be mindful of where and how you dump it. This water is a little gross, but nothing compared to…

Black Tank

…the black water in your black tank. As mentioned, this is where you’ll find human waste and sewage from your rig. There are strict rules and laws about how and where you can dump your blank tank. Black tanks require periodic maintenance with special cleaners and deodorizers to prevent buildup.

Happy Campers RV Toilet Treatment - 64 Black or...
  • ODOR FREE: Eliminates odors in the RV holding tank. Absolutely no...
  • Septic tank friendly
  • EFFECTIVE: In extreme hot & cold temperatures ( over 100 Deg)

Pro Tip: Get the best water quality in your RV by discovering Should You Have a Reverse Osmosis System for Your RV?

RV Waste Water and Dumping

Ok, you’ve used your water. Now what? Your tanks can hold this wastewater while you camp. Once you’ve filled your tanks or finished your trip, it’s time to dump them. Most RV parks and many campgrounds will have dump stations, and others are also available in places like highway rest stops or certain outdoor shopping chains. 

Make sure to put on rubber gloves for this – you’re handling raw sewage, after all. Use a sewer hose to connect your RV’s tank valve to the dump station, and dump away. Always empty your black tank first, followed by your grey tank. This allows you to use your grey water to flush the remains from your black water out of your hoses. It’s also good practice to rinse your sewer hose with fresh water after dumping.

Man at RV dump station dumping tanks
Man at RV dump station dumping tanks.

Enjoy Your RV Water!

As you can see, there’s a bit more to think about with your RV water system compared with your home. But if you keep these guidelines in mind, you’ll be enjoying hot showers and refreshing drinking water in no time – with minimal toilet water issues!

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About Tom Morton

Tom, a Pacific Northwest native, is our technical genius. Born in Washington and raised in Alaska before settling in Michigan. He's the man who keeps our operation running, both figuratively and literally.

With a background in Electrical Engineering, Tom specializes in RV solar systems and lithium batteries. He made history as the first documented individual to use a Tesla battery module as an RV battery. Tom has personally assisted countless RVers with system installations and has educated thousands more through his videos and articles.

Cinematography is another of Tom's passions, showcased in his work on the Go North series. You can see his camera skills on display in The RVers TV show on Discovery Channel and PBS where he also stars as a co-host.

Tom's mechanical expertise extends beyond RVs to boats, planes, and all things mechanical. He's renowned for taking on maintenance and repair projects single-handedly and is often spotted underneath RVs, making him the technical backbone of our endeavors.

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Wednesday 1st of March 2023

Thank-you, that was very good, and since I am new to very helpful.

Jim Ryan

Thursday 6th of May 2021

Just as any FYI, your link for Truma AquaGo On-Demand Tankless Water Heater takes you to 6 rv toilet types:

Mortons on the Move

Friday 7th of May 2021

Thanks for letting us know. We've corrected the link.

Clay Autery

Saturday 13th of February 2021

It just occurred to me, that for those who like boondocking but choose NOT to put in a composting (or other) toilet, that another way to save fresh water would be to add a supplemental pickup screen, line, boost pump, and 2-way valve (with BPV on both inlet legs) so you could CHOOSE whether to flush the toilet from the freshwater tank OR the grey water tank.