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Should Your RV Tank Valves Stay Open at a Campground with Full Hook-Ups?

If you’re a newer RVer, you may look at full hookups as an opportunity to keep your RV’s tanks open for the duration of your stay.

Imagine it. You’ve just pulled into your spot at a new RV park. It’s got gorgeous views, lots of amenities, and full electric, water, and sewer hookups. Keeping the RV’s tank valves open is one less thing to worry about. Right?

Wrong, unfortunately.

Read on to learn more about why this could cause some serious and unexpected problems for your rig.

Let’s dig in!

Should You Leave Your Black Tank Valve Open When Hooked Up?

It might seem convenient, but you should never leave your RV’s black tank drain open while hooked up. This can cause a variety of gross and expensive problems, including the dreaded “poop pyramid.” This happens when the liquid waste flows out of your black tank into the sewer system.

This leaves solid waste to get stuck on the bottom of your tank. Over time, this waste builds up and can cause serious clogging issues. 

You can fix this problem by allowing your tank to fill with water, leaving it to soak, and then flushing. You can also sometimes use special tank cleaners. But serious cases could damage your tank, leading to expensive repairs or replacements. 

PRO TIP: Here’s an article all about the RV poop pyramid.

Additionally, when you leave your RV tank drain open, sometimes sewer gas can escape from the park’s sewage system. Most of the time, a p-trap will help prevent these gases from rising. But they’re not foolproof, especially in RVs. Plus, sewer gases can still escape through your tank’s exterior vents, creating an unpleasant situation for you and your neighbors. 

Finally, leaving your black tank valve open can even lead to some unwanted guests — drain flies! These pests can enter your rig’s black tank via the open connection to the sewer and lay their eggs. From there, it’s only a short flight up into the living space of your RV. Keeping your tank valve closed is an easy way to prevent an infestation. 

Should You Leave Your Gray Tank Valve Open When Hooked Up? 

While you may not have to deal with all of the same problems as with your black tank, keep your gray tank closed too. This helps avoid unpleasant sewer odors but also helps simplify the cleanup process of dumping your black tanks.

Letting your gray tank fill and drain helps flush out food particles or other solids that slipped down the drain.

Benefits of Full Hookup RV Parks

Even if you don’t leave your RV tank valves open, it’s still great to stay at full hookup parks. Of course, that depends on your budget and travel plans. 

Ability to Use Water Freely

If you’re operating off your freshwater tank instead of an exterior water source, you’ll constantly scrutinize every drop you use.

However, with full hookups, you can use as much as you need. So take that long shower, wash extra dishes, and even boot up the washer and dryer if you have one. You can do it all without worrying about running dry.

Keep in mind: All water sources aren’t equal. Get a filter for any water you let into your unit.

Ability to Dump and Rinse Your RV Tanks Without Holding Up Others

Sitting in line at a dump station is no one’s idea of a good time. But with a full hookup park, you won’t have to. Instead, you’ll be able to fill, open, dump, and clean out your RV’s tanks without ever leaving your spot.

This means you can do it on your own schedule and not have to worry about holding up other RVers or having them slow you down. It may seem like a minor issue, but little conveniences like this add up over time.

Ability to Shower in Your RV

Trekking to the campground shower can get old fast, especially in cold weather, bad weather, or early mornings. However, with full hookups, your RV will have a functionally unlimited supply of fresh water. You can shower as long as your heart desires.

Plus, the already-pressurized water means you’ll have a constant, steady flow, as opposed to the fluctuations that can result from many RV water pumps.

Tips for Dumping Your Black Tank at a Full Hookup RV Campground

The secret to easily dumping your black tank in a safe and sanitary way lies in your gray tank. The process starts a day or two before you plan to dump your black tank. That’s when you should close the valve in your gray tank, allowing gray water to accumulate.

When it comes time to dump your black tank, open your blank tank valve and allow the tank to drain. Once that’s complete, drain your semi-filled gray tank using the same hose.

This process flushes out any remaining sewage inside your hose and leaves you with two empty tanks. 

Staying at a full hookup RV park can be a great experience. But just because you’ve got access to a sewer system doesn’t mean you should keep your tank drains open.

From major clogging to odors to bugs, you can run into any number of issues by leaving your valves open. Have you ever encountered these issues at a campground?

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  1. Al LeFeusch says:


  2. Jonathan Powell says:

    I have a reason to, we were at a park with full hook up and it rained a lot and their sewer backed up and if we had of had our drain open it would of backed up into our rv which would of been a bad thing. Luckily I read your page on rv drains and had ours closed. Thanks for your information on rv tanks. And also turn off the water when leaving the rv unattended,just incase something breaks or bust.thanks again for all your articles I received.
    Jonathan Powell