How to Drain an RV Fresh Water Tank

Posted on September 24, 2020 by Daniel Renfro in Guides

RVs give you a lot of freedom to travel and explore, not to mention making camping and vacations a lot more comfortable. But that’s only true when you properly maintain your RV, including its water system. After all, dirt water in your RV is a recipe for illness and discomfort on the road.

Taking care of your freshwater tank is one of the most important parts of regular RV maintenance, especially if you use your RV tap water for drinking water. You need to take a few extra steps to properly drain your fresh water tank to help keep it clean and sanitary for your next use.

There are also a few different steps you might need to take depending on what other maintenance you’ve done on the water tank, so I’ll talk about those too.

Let’s get started!

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How to Dump an RV Fresh Water Tank

First, I want to mention that there are two other water tanks on your RV that also need regular maintenance, but the steps aren’t the same. Your gray water tank and black water tank both need special maintenance to keep them working properly and as sanitary and safe as possible.

The maintenance I’m talking about in this article is only for your freshwater tank.

1. Locate Your Fresh Water Tank

There are two possible locations for your freshwater tank. It might be housed inside your RV where it can benefit from better insulation and protection, or it might be underneath your RV to give you a little more space inside.

Your owner’s manual should tell you where to look for your fresh water tank in your RV, but if you bought your RV used or don’t have the owner’s manual it should still be fairly simple to find your fresh water tank.

If it’s housed inside your RV it will typically be under the RV couch or under a dinette in your kitchen. You’re looking for a fairly large white tank with several different hoses and valves sticking out, and a small water pump attached.

If your water tank is underneath your RV tank it should be even easier to locate. Your other two water tanks will be clearly marked to prevent confusion. Your freshwater tank will be white, fairly easy to see, and may also be labeled as your freshwater tank.

It may be right next to your other water tanks, or somewhere else entirely on the bottom of your RV, it all just depends on your RV’s interior set up and where it makes the most sense to include the tanks.

2. Find the Drain Spout

Now that you’ve found your fresh water tank, the next step is finding the drain spout. Usually, that isn’t too difficult, but it may be trickier if your water tank is housed inside your RV.

For tanks inside of the RV, grab a flashlight the first time you want to find the water tank drain spout. You’ll probably need it to see around the corners and find the spout.

Usually, the drain spout will be a bottom corner of the tank, but it could be on any accessible side of the tank. It’s just a normal white spout with a turn handle just like you’d find on a water cooler. There are several other hoses attached to the tank as well, so make sure the spout you’re looking at is attached directly to the water tank and nothing else.

It should also be a spout, not a value. Your winterizing valve isn’t a good option for draining the fresh water tank.

3. Open and Let the Water Drain

If your fresh water tank is inside your RV, the next step is to make sure there is a drainage point for the water to exit the RV. Sometimes the drainage point will be open, but there may also be a plug or a valve that you’ll need to open before you can open the drain spout.

Take a look around the tank to see if you can see a hole near the spout or a plug. If there is a plug or drain, make sure it’s open and then drain your tank. Stay and watch for a minute or two while the water drains to make sure it isn’t building up inside the water tank’s housing.

If your tank is outside of the RV, just go ahead and open the spout on your water tank and let it drain. Even water that has stagnated in your freshwater tank or developed an odor is safe to dump pretty much anywhere.

If there’s a noticeable odor to your freshwater tank you should avoid dumping right next to a drinking water reservoir or anywhere the scent might linger, but it’s unlikely that there’s anything in your freshwater tank than can cause harm, unlike your gray- and blackwater tanks.

4. Sanitize the Tank

You may not need to sanitize your fresh water tank every single time you drain it, especially if you only use chlorinated water from a filtered source. But, if you’re emptying your fresh water tank to get rid of winterized water, notice an odor while it’s draining, or have allowed the water to stagnate in hot weather, you should rinse and sanitize the tank after you drain it.

The most common way to sanitize your tank is to add a little bleach, fill the tank, let it sit, and then drain the tank and rinse it several more times.

Bleach can be harmful, so you may want to use a drain pan or hose to help direct the bleach-water mixture instead of just dumping it just anywhere.

You’ll also need to fill the fresh water tank several times and drain it to clear out the last of the bleach residue. Plan on at least 3 fill-drain rinsing cycles before you’re done, but ideally, you should keep rinsing until the water coming out of your tank doesn’t have any lingering bleach smell.

That’s it, folks! You’ve drained and sanitized your freshwater tank. It’s ready to re-fill and take with you on your next RV adventure!

Where is my RV’s fresh water tank drain?

The freshwater tank drain can be a lot of places, but it will always be on the bottom of the freshwater tank.

Usually, the drain will be relatively close to the corner of the tank to make it more likely that you’ll be able to drain all the water out. It’s important to get the tank dry since even 500mL of water can be enough for bacteria and algae to grow.

Why is my RV’s freshwater tank full?

Your freshwater tank might fill for several reasons if you’re connected to a water source. Usually, the issue is that your quick fill valve was left open when you connected to the water source. However, occasionally a check valve might have been damaged or fail.

If your check valve does turn out to be the problem, you can replace it with an in-line check valve instead of replacing the whole water pump system.

How long can you leave fresh water in an RV tank?

There are a lot of factors that can influence how long water is safe and sanitary in your freshwater tank. If you’ve been sanitizing the tank regularly and only use water from reliable, chlorinated, water sources you can generally count on your water being safe for two weeks.

However, if you notice any changes in odor, taste, or color of the water in your freshwater tank, you should drain, sanitize, and refill the tank from a fresh source.

How do I stop my freshwater tank from filling up?

Chances are if your freshwater tank is filling unexpectedly you have one of two problems. You may have left your quick fill valve open, in which case closing the valve and draining the tank should take care of it.

But, if your valve is closed and the tank still filled, you probably have a faulty check valve. Your check valve is often integral to your water pump system, so it’s not always as simple as pulling out a valve and replacing it.

Fortunately, there are in-line valves that will replace the function of a faulty check valve without having to replace the whole pump. Install one of those and you should be good to go.