RV Gray Tanks: The Other RV Waste Tanks

As RVers, we all spend a lot of time talking about the RV black tank.

But the RV gray tanks can be just as big, if not bigger problem, than the black tanks.

Tips and tricks for maintaining your RV gray tanks.

Disclosure: This post contains affiliate links for various products below. You get the same low prices and we earn a small commission to help us buy more RV tailgating gadgets. Or game tickets if you go on a shopping spree.

For the RV Newbies

A quick aside for RV newbies: most RVs have two different types of waste tanks: the black tank and the gray tank.

The black tank is the waste from the toilet. The gray tank is the waste water from the sinks and showers.

We all spend a lot of time talking about black tanks because well, poop. And we never really evolved past third grade humor, right?

There is the ongoing debate on toilet paper (I think any septic safe toilet paper is fine in the RV, no need to get special, expensive RV safe toilet paper). And the debate on the best black tank treatment (I think RV Black Tank Cleaning Bombs are well, the bomb!).

Gray tanks can build up smells just like a black tank.

And because the smell itself could vary widely, depending on what you rinsed down the sink, you may not even know where the smell is coming from.

Avoiding Gray Tank Smells

The first step to avoiding a smelly gray tank is to keep food and other stuff out of the tank.

There are two main ways to avoid getting food in the gray tank:

  1. The best thing to do is to make sure you wipe down your dishes before you begin washing them. Use paper towels or paper napkins to wipe off leftover food scraps and even sauces.

    Depending on your setup, you may also want to rinse your dishes outside, with either a portable sink or the outdoor shower.

  2. The second best thing is to use sink strainers to catch leftover food particles. These sink strainers will catch some of the smallest of food particles that end up in the dish water.

See Also: Tips for Dealing with RV Odors

Whatever you do, make sure that no shrimp peels go down the drain. Ask me how I know…

From the Bathroom to the RV Gray Tank

Don’t forget about the RV bathroom!

The bathroom sink should have it’s own strainer as should the shower.

You definitely want to keep long hair out of the RV gray tanks and pipes. I like the OXO Good Grips Shower Drain Protector because it lays flat and the non-slip rim stays in place even if you step on it.

Unlike the sinks, the RV shower drains typically have a wide flat guard that keeps the sink strainers from working.

See Also: Upgrade Your RV Shower to an Oxygenics

Beauty Products

You need to be careful about what beauty products you use in the RV. Beauty products that are full of coconut or other oils can do some serious damage on RV gray tanks and RV plumbing.

Think of the build-up the oil can leave just on the surface of your shower. Now imagine that it all builds up in your gray tanks or your pipes.

Hint: If you do use coconut or other oil based products, make sure that you use really hot water well past the time you think you have drained it all out of the shower or sink to wash the oil out of the pipes.

Then you’ll want to dump as soon thereafter as you can, particularly if you are in a full hookup RV campground so that you can get the oil out before it cools and hardens.

Bottom line: use oil products in moderation.

Rinse Off Before Your Shower

If you’ve been out at the beach or out in a muddy lot, rinse as much of the sand, dirt, and other grime off with the outdoor shower.

Generous use of the outdoor shower means less of all that dirt in your gray tanks. All the used water will also end up watering the grass around your RV site instead of the gray tank.

This is especially helpful in extending the use of your gray tank if you are boondocking.

See Also: Tips to Save Water While RVing

Use Dawn Soap

Most of the time, I say you can get away with store brands for most products. However, I highly recommend that you use Dawn Soap.

The straight up blue dishwashing soap is definitely the best when it comes to cutting down grease and anything else you might get in your RV gray tanks.

Since most of us don’t have dishwashers in our RVs, we hand wash the dishes. And a sink a day of dirty Dawn dishwater will help fight problems in your RV gray tanks.

Dawn will help breakdown grease from food and oils from your food and beauty products. It’ll also help with odor.

Use the Right Laundry Detergents

If you are lucky enough to have a washer and dryer in your RV, you’ll be glad you did after that first rainy tailgate.

But you’ll need to know a few things about them: mostly, they don’t use nearly as much water as the household counterparts.

This means that you don’t have nearly the dissolving power that a home washer does.

So you don’t want to use Tide pods (and hey, at least your kids won’t have them available to eat either). The Pod packaging has a bad habit of not dissolving, letting the packaging build-up in your pipes. That would be a bad situation for any RVer!

Instead, you’ll want to use a high-efficiency liquid laundry detergent. The high efficiency detergent is specially created to be low sudsing and quick dispersing. HE detergents also keep soil in suspension, even in low water levels, so the dirt doesn’t get back on your clean clothes.

I really like the new Tide Liquid Laundry Detergent Smart Pouches. They take up a lot less space in your RV, where storage is always at a premium. They are also more environmentally friendly, since they have 60% less packaging than a standard bottle.

Also, remember that RV washers are typically much smaller than their household counterparts. This means less volume for not only water, but also your clothes or linens. You don’t need as much detergent, even HE detergent, in an RV wash that is in a Tide Pod. I usually use about a third to a half of a regular dose of detergent. You’ll want to experiment over time to find the ideal level for your clothes.

But don’t be surprised if it is much smaller dose of detergent than you would at home.

Dumping RV Waste Tanks

While I am quite stingy with the water during the tailgate or camping trip, at the end of a tailgate weekend or the end of any camping trip, I make sure that I finish off the water that I have in the fresh tanks into either the black tank or the gray tank (or combination thereof).

Water really does keep these RV waste tanks working best by allowing a full flush when you dump.

I find that the best time to dump RV waste tanks is after some driving. Instead of staying stationary, driving and all the momentum and movement that goes with driving, means that the contents of the tanks get nice and mixed up. Any solids that have been able to sneak their way into the tanks are stirred up and held in suspension for when you dump instead of sitting on the bottom.

You’ll always want to empty your black tanks first so that you can rinse out the hoses with the far less yucky (yes, that’s a technical term here) contents of the gray tank.

But you will also want to protect your gray tank by closing the black tank before you empty the gray tank. This will prevent backflow of contents. Because the last thing you want is for some of the black tank contents to end up in your gray tank.

Remember to add a few gallons of fresh water to the tanks after you are done dumping to keep everything in good shape.

See Also: Essential Gear for RV Waste Tanks

Camping with Full Hook-Ups

If you are in a campground with full hookups, there are a few extra things for you to consider.

Leave Gray Tank Closed

I recommend that you do not camp with the gray tank open. I know a lot of people do, but hear me out here.

If you leave it open, you won’t have any gray water to flush out the hose when you empty the black tank. To remedy this, many people will close the gray tank a day or two before dumping their black tanks.

But I still recommend that you leave it closed all the time, except when you are actively dumping.

Some campground sewers have been known to host quite a few pests. And who wants sewer bugs crawling up into their RV tanks and even into the RV living space? Yeah, no thanks.

And not just pests, but odors too. No thank you.

Still Having RV Gray Tank Odor Problems?

If you are still having problems with your RV gray tanks, try dropping a Black Tank Cleaning Bomb in your sink and letting the cleaning awesomeness of the Cleaning Bomb do its job on the gray tank.

Most new RVs have black tank rinse systems. But these are usually not on the gray tanks. However, you can help the gray tank along by running fresh water through the system. You may need to dump, refill, and dump again. Maybe even multiple times to get all the stuff (yes, those technical terms again) out.

See Also: Spring Cleaning Tips for Your RV

Air Admittance Valve

Some odors may not be from the gray tank itself but instead of the pipes. Make sure your air admittance valve (AAV) is sealing properly.

The air admittance valve is usually found under your sinks on the piping. As the water drains down, there will be some piping that sticks up. This is where the AAV attaches. As you can see from the picture to the left, it looks pretty plain – just a cap on the vertical pipe.

If the valve is working correctly, it should allow air into the pipe to allow water to freely drain. Then when done draining, the valve closes to stop smells from coming into the RV. You might need to replace the AAV if it is not working correctly.

Fortunately, if this is the case, the AAV is usually pretty cheap and under $10. It is an easy DIY fix.

Count the Gray Tanks

Finally, some RVs have more than one gray tank!

So make sure you are dumping both of the gray tanks. Leaving stale water in the gray tank because the tank is rarely used is a sure fire recipe for a smelly RV.

See Also: Review RV Remote Temperature Monitoring Systems

Got Questions?

How to maintain your RV gray tanks - tips and tricks to keep the RV gray tanks working and not smellingIf you have more questions about maintaining your RV gray tank, please ask in the comments below. If you have a question, there are lots of other people out there that have a similar question.

Let’s help each other out by talking them out!

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Kimberly

Kimberly is the owner of a Tiffin 34PA and the former owner of Starter RV, a 1990 Winnebago Chieftan. She can be found cheering for Georgia Tech, traveling the world, or working on the RV (because there's always something to do on the RV). Don't ever underestimate what she can whip up in the kitchen or accomplish on no sleep. Find out the latest from Kimberly by signing up here.

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