How to Fill Up Your RV’s Fresh Water Tank

Shelley DennisOctober 2, 2022

How to Fill Up Your RV’s Fresh Water Tank

As a new RVer, there are so many things to learn about your travel trailer or motorhome. While the best way to learn is by doing, it certainly helps to also do a little research before diving in head first. In this article, we’re going to talk about one of the most basic systems on your rig: the RV fresh water tank.

And if you’re looking to try RVing for the first time, check out this filter on our site that’ll help you pick the best RV for you.

RVs For Rent Near You

{“odcTracking”:”How to Fill Up Your RVs Fresh Water Tank”,”rentalPageType”:”pin”,”odcLocale”:”en-us”,”partnerId”:”700″,”apiObject”:{“auto_radius”:true,”instant_book”:true,”pagination”:{“pageSize”:4}}}

Every camper is designed a little differently, but most include a freshwater tank. You’ll use this handy system for drinking, cooking, doing dishes, showers, and using the toilet when you are not hooked up to an outside water source. Learning how to fill and care for the fresh water tank is a definite necessity.

What is an RV freshwater tank?

Before we dive into how to fill your fresh water tank, let’s talk a little more about them and the other tanks you’ll find. There are usually three types of tanks on an RV:

  • Fresh water tank: This is self-explanatory— it’s a tank that’s filled with fresh water. The water stored in this tank comes out of your taps.
  • Grey water tank: The grey water tank is where your used water from the sink and shower go.
  • Black water tank: The black water tank is where the waste from your toilet ends up. If a camper doesn’t have a grey water tank, the used water will end up here as well.

The whole RV freshwater system is more than the tank, though. In order to draw water from the tank to your faucets, the system is also equipped with a water pump. Most people also use water pressure regulators if hooked up to city water, and many people have RV water filtration systems.

If you’re lucky, the water will also go through a water heater, which will allow you to have nice and warm showers. You might even have a water level monitor, which lets you know how much water is in your tank without having to physically look inside.

Using City Water Supply in an RV

If you are at a campsite with a water hook-up, there’s no need to worry about your RV fresh water tank. Most RVs have their water intake valves situated one of two ways. Some have separate connections for filling up the tank or using city supply. Others use the same connection but have a valve that allows you to switch between the two.

If you’re using city water and you have an intake valve, switch your intake valve to the option that says “city supply” or “local supply” and turn your water pump off. You only need to use the water pump when you are using water from your fresh water tank. In other words, if you have hooked a hose up to your RV at a campsite and are using city water, you are bypassing your fresh water tank. The pressure from the city spigot will push water through the hose and throughout your rig when you turn on a faucet or flush.

It’s also a good idea to have a water pressure regulator like this for your RV. That’s because campground water connections often have high pressure that can damage your RV plumbing. A regulator makes sure that the water entering your RV is always at the proper pressure.

How do you fill an RV fresh water tank?

Using your water tank comes in handy if you aren’t going to be using a hook-up at your campsite. But a freshwater tank doesn’t do much good if it isn’t filled with water!

Keeping RV Hoses Separate

Before you go looking for your freshwater fill valve, there’s one concept that is very important to know: separate hoses. You should have a hose like this that is dedicated entirely to your freshwater system. Do not use this hose to clean out a septic hose or even for washing your RV. Typically your fresh water hose will be white, however, some come in blue. Just make sure you keep it separate to avoid contamination of your drinking water.

Step One: Locate the Intake Valve

Once you’ve designated a hose for drinking water/fresh water, attach it to the fresh water intake valve (sometimes labeled “city water”).  Attach the other end of the hose to your water spigot.

In the picture below, there is a lever that you can pull to fill or to bypass the water tank when hooked up at a campsite. If you have a lever, make sure its opened to let water into the tank.

Photo Tripping America - Fill the Fresh Water Tank - Outdoorsy

Step Two: Keep an Eye on the Water Level Monitor

Before you open the spigot, locate your tank indicators inside your vehicle. Remember: tank indicators are notoriously inaccurate and visually seeing how full your tank is will always be more accurate than an indicator. Try to get a visual read on your tank if you can. If you have no visual, then use the tank indicators on your panel in the RV to tell you when the water tank is approaching full.

Step Three: Fill ‘Er Up!

Turn the hose on from the source and fill ‘er up!

Depending on how big your fresh water tank is, you may want to think twice about filling it completely up. Water weighs over 8 lbs. per gallon so it can add quite a bit of weight to your rig as you are traveling down the road. If you are headed to a boondocking site, where no water will be available, a full tank may make sense.

But if you are headed to a nice national park campsite with water and electrical hook-ups, you may want enough fresh water to drink, cook and use the restroom until you arrive at the campsite, but no more. Plan ahead.

Photo Tripping America - Fill the Fresh Water Tank - Outdoorsy

When the tank gets close to full, be sure you are outside your vehicle with plenty of time to turn off the spigot. You never want to overfill the tank. Leave the tank valve on “tank fill,” unhook the hose and store it away from your septic hoses. It’s usually a good idea to store them in completely separate compartments, if possible.

Using an RV Water Pump

A lesson in water use within your motorhome or travel trailer includes a little knowledge about your water pump. Your pump can run off of a battery, meaning you don’t need to be hooked up to shore power. Somewhere within your vehicle is a switch to turn the water pump on and off.

When using your RV water tank, make sure the pump switch is flipped on. When the pump is turned on, you will hear it every time you turn on the water within your vehicle, such as when you run the water faucet or flush the toilet. It will stop running when you turn the faucet off or when the toilet is finished flushing. If you hear it when no water is running in your rig, you may have a water leak somewhere.

Cleaning Your RV Fresh Water Tank

Sometimes water can pick up a smell when it’s been stored for a while. If this is the case, you can drain the fresh water tank and use something like AquaShock Freshwater tank sanitizer to get that thing squeaky clean. There should be a drain near your fresh water intake valve that allows the fresh water tank to drain on the ground before you refill the tank.

Here is a great video from RVGeeks teaching you how to go through that entire process:


Well, you’ve conquered the freshwater system in your new RV, and you did it without floating away. Now you can move on to more exciting activities, like finding the perfect RV for your first camp trip. Happy travels!

I'm a mountain gal who gave it all up to hit the road full-time with my Golden Retriever, Sully. Together we explore the back roads of America, documenting the beauty of our country and the people that make her great!

Ready to get started.

Be the first to get doses of destination inspiration, and discount codes.

We care about the protection of your data. Read our privacy policy