How to Drain a Fresh Water Tank on an RV – Step-by-Step

A white RV parked in grass with a blue canopy over top. Lawn chairs and a fold-up table sit under the canopy.

When you go on an RV vacation with your family, the last thing you want to deal with is a water tank issue — this can quickly put a damper on your trip and could even cut it short. To avoid water tank problems, it’s important to keep your RV’s fresh water tank clean and free of contaminants, and the best way to do that is by draining it regularly. 

In this article, we’ll discuss why you should drain your fresh water tank and how to do it. We’ll also provide some tips on keeping your tank clean between drains. So read on for all the information you need to ensure your RV trip goes on without a hitch!

What is an RV Fresh Water Tank?

Every RV has a fresh water tank that stores water for drinking, cooking and bathing. 

Most tanks are between 30 and 60 gallons, and the size of the tank will determine how long you can go without needing to refill it. To fill the tank, you’ll need to connect the hose to a water source. Once the tank is full, it’s important to properly maintain it to keep the water clean and potable. One way to do this is to regularly drain the tank and flush it with fresh water.

How Long Can Water Sit in a Fresh Water Tank Before It Becomes Contaminated?

As any experienced RVer knows, it’s important to regularly drain and clean out the fresh water tank on your RV. If water sits in the tank for too long, it can become contaminated with bacteria that can make you sick. In addition, water sitting for extended periods in a plastic tank can eventually take on the smell and taste of plastic. 

So how often should you drain your water tank, and how long can water safely sit in the tank before it becomes a health hazard?

The general rule of thumb is that water will stay fresh in the tank for about two weeks if you aren’t refilling it regularly. If you use it regularly, thereby resupplying it daily, you should be fine. Freshness and safety become an issue when you have stopped using the RV, and it sits for an extended period.

If you’re worried about the safety of your water, there are a few things you can do to ensure it doesn’t become contaminated. First, always use fresh, clean water when filling up your tank. Second, be sure to regularly prop open the drain valve on your tank to allow any built-up sediment to be flushed out. Finally, consider installing an inline water filter on your RV’s freshwater system.

Steps to Properly Drain Your Fresh Water Tank

If you’re like most RVers, your fresh water tank doesn’t occupy your mind until it’s time to fill it up. But if you don’t properly maintain your tank, it can become a breeding ground for bacteria and other contaminants. That’s why it’s important to drain and flush your tank regularly. 

Here’s a step-by-step guide to draining your RV fresh water tank:

A white RV with a canopy covering two black chairs and a table. The RV sits in a grass lot surrounded by trees.
  1. Before draining the fresh water system, turn off the hot water heater and then the main supply valve. This will keep any new water from entering the tank while you drain it. Make sure your heater holding tank has cooled down before proceeding.
  2. Flush the toilet until water stops coming out of it.
  3. The next thing you’ll want to do is open all the faucets in your RV, including any outside showers, to start draining the water from your tank. The drains are located beneath your RV at what we call the low-point drains. You can usually tell them apart from other hoses by their red and blue coloring, as well as the small plastic caps or valves that keep them shut when they’re not in use. To let the water out, simply unscrew the caps or turn on the valve.
  4. Once the water has started draining, turn on your RV’s pump to help empty the tank more quickly.
  5. Continue running the pump and draining the water until the flow from the faucet slows to a trickle.
  6. Now it’s time to flush out the tank with clean water. Turn off the pump and open the main supply valve to let fresh water into the tank. Run the pump and all the faucets until the water coming out is clear.
  7. Unscrew the water heater drain plug and empty it.
  8. Finally, turn off all the faucets and close the main supply valve. Your RV’s fresh water tank is now empty and ready for refilling!

Tips for Keeping Your Fresh Water Tank Clean Between Drains

Keeping the tank sanitized regularly ensures that the water you store in it remains clean. Follow these procedures to ensure that your water stays safe:

  1. Pour a ¼ cup of bleach into your tank for every 15 gallons of capacity.
  2. Using city water, fill your fresh water tank.
  3. Allow the bleach and water mixture to sit for eight to 12 hours, before turning on all your faucets at once and draining the mixture out.
  4. Lastly, run the water through all the faucets to wash away any obstructions. To complete this process, run the water until it no longer smells of bleach.
A black RV with a gray pattern on the extended slide-out components. White curtains shade the front window.

Tank Depot Carries RV Fresh Water Tanks

A white, rectangular water tank with a circular opening on the side.

If you’re looking for a new fresh water tank for your RV, our experts at Tank Depot have you covered. We carry a wide variety of tanks in various sizes, so you can find the perfect one for your needs. We also offer a wide range of accessories, including tank valves, fittings and more. 

Visit our website today to browse our selection and place your order. We’ll ship your new tank right to your door, so you can get back on the road in no time! Contact us today for more information.