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How To Fill the Fresh Water Tank

As a new RVer, there are so many things to learn about your travel trailer or motorhome. It can be overwhelming at first. That’s why Outdoorsy has created a new series entitled “One Big Question,” where we tackle one new action, walking you through what sometimes seems to be a daunting task.  Today’s question is:

How can I fill up my freshwater tank?


There are so many systems in an RV that sometimes we forget the most basic…water. Every camper is designed a little differently, but each has a freshwater tank. You’ll use fresh water for drinking, cooking, doing dishes, showers, and using the toilet when you are not hooked up to an outside water source. So learning how to fill the freshwater tank is a definite necessity.

Photo Tripping America - Fill the Fresh Water Tank - Outdoorsy

Don’t Mix

Before you look for your freshwater fill valve, there is one concept that is very important regarding water. You should have a hose that is dedicated entirely to your freshwater system. Do not use this hose when cleaning out a septic hose or even for washing your RV. Keep it separate so that you don’t risk contamination of your drinking water.

Once you’ve designated a hose for drinking water/freshwater, attach it to the freshwater intake valve (sometimes labeled “city water”).  Attach the other end of the hose to a water spigot. In my RV, I have a lever that I can pull to fill my tank or to bypass my water tank when I hook up at a campsite.

Photo Tripping America - Fill the Fresh Water Tank - Outdoorsy

How Full Is Full?

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. My tank is under my bed, so I can lift the mattress and see the water filling the tank. 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.

Fill ‘Er Up!

The freshwater intake valve has a lever to allow you to fill the tank or bypass the tank (when you are using water directly from the spigot). Make sure it is set to fill your water tank, then turn the hose on and fill ‘er up!

Depending on how big your freshwater 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 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 – I put mine in an entirely different section of my RV basement.

Pump You Up

A lesson in water use within your motorhome or travel trailer includes a little knowledge about your water pump. Somewhere within your vehicle is a switch to turn the water pump on and off. I have one on my monitor in the kitchen and another in the bathroom. Find this switch, which can be used on 12-volt power (battery), so you don’t have to be hooked up to shore power.  When the pump is turned on, you will hear it every time you turn on the water within your vehicle, for such things as running the water faucet or flushing 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.

You only need to use the water pump when you are using water from your freshwater tank. In other words, if you have hooked a hose up to your RV at a campsite and are using “city water” (bypassing your freshwater tank), you do not need to run the water pump. The pressure from the city spigot will push water through the hose and throughout your rig when you turn on a faucet or flush. You only need to use the water pump when you want to use the water stored in your tank. In the case of a city water hook-up, you may want to consider adding a water filter between the spigot and your hose to take out minerals from local water systems.

Clean Water

One other consideration is cleaning your freshwater tank periodically.  Sometimes water can pick up a smell when it’s been stored for a while. In that case, you can drain the freshwater tank, run water with a small bit of bleach through your system, then refill the tank as described above. There should be a drain near your freshwater intake valve that allows the freshwater tank to drain on the ground before you refill the tank. Here is a great video teaching you how to accomplish that entire process:

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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 planning your first camp trip!

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