8 Tips for Flushing RV Grey and Black Tanks

Flushing RV Grey and Black tanks isn’t difficult but I know I was nervous the first time I had to do it since it’s not something you want to mess up. Once you understand how they work and follow the steps and tips you shouldn’t have any trouble if you just pay attention to what you’re doing. However, if you do steps out of order you could potentially have a big mess to deal with.For example, I’ve seen people open the valve before removing the tank cap on the RV. You’re guaranteed a mess at that point – how much depends on whether you catch the mistake and close the valve before removing the cap. If you do, you’d just have to deal with the amount of waste that’s filling the space between the valve and the cap. If not, well…it’s going to be ugly.

8.  Maintain Your Tanks

The plumbing system in your RV is not as robust or forgiving as your household plumbing. Don’t flush any female sanitary items because they don’t break down well enough. They can cause issues for your RV’s system as well as the campground’s sewer or septic system.

Use a black tank sprayer occasionally for a more thorough cleaning. These are useful to remove buildup on the sides of the tank and on the sensors that read the fill level of the tank. Also, there are many products on the market that can be added to the tank to help with breaking down materials in the tank and odor control.

7.  Choose Your Toilet Paper Wisely

You should use a type that breaks down quickly and adequately. Surprisingly, the super-thin RV/marine paper I’ve been using may not be the best or only option as seen in the video below. The performance of Charmin Ultra impressed me!

6.  Use a Reverse Flush Valve

I bought the Valterra Flush King valve and it was a game changer. I was shocked the first time I used it and discovered how much wasn’t getting flushed out of the black tank by just opening the valve.

5.  Get a “Sewer Tote”

I use a Rubbermaid container with a latching lid to store all of my sewer-related items. It keeps them organized and avoids contaminating other items in the storage compartment. It’s an easy way to quickly grab everything I need when at a dump station or setting up at a full hookup campsite. See my list of recommended RV sewer items here. (coming soon!)

4.  Don’t Leave the Valves Open at a Site with Sewer Hookups

It might seem like a good idea so you don’t have to go out and dump the tanks every time they fill up but there are a couple problems with it. First, you’ll have the issues mentioned in the last tip because the liquids won’t stay in the tank but the solids will and they will accumulate and harden. Also, if the valves are left open, the unpleasant gases will have a clear path from the open sewer system up through the pipes and out the sink and tub drains into your RV living space.

3.  Don’t Leave the Black Tank Empty

Don’t get me wrong, you definitely want to flush all the waste out of the tank but you’ll have better results if you keep some water in it. Think about the black tank like a large version of your toilet bowl at home. The difference is that the black tank contents are out of sight but if you don’t have water in either one and it’s used multiple times between flushes, things will start to accumulate and dry out forming the dreaded “poo pyramid”. This can be very difficult to remove and can cause issues with the sensors that indicate the fill level of the tank.

Having water in the tank will help break down toilet paper and waste and keep it from drying out. The water will also help transport the solids out of the tank when you flush it. If you leave water in the tank when leaving the campground, the sloshing motion from driving should help, too. I leave a good amount of “clean” water in the tank all the time. This helps keeps waste from building up and I just dump the tank as soon as I get to the next campground.

You can add water to the black tank through a reverse flush valve, a prolonged toilet flush or even just dumping water straight down the toilet. Just remember to leave it completely empty at the end of the season if you’re in a climate where you need to winterize your RV.

2.  Don’t Leave the Dumping Process Unattended

I know that once things start flowing it’s tempting to step away to do something else – don’t do it! If a connection comes loose you need to be ready to close the valve quickly to minimize the mess and avoid coming back to a disaster.

1.  Wear Gloves

When dumping the tanks there’s obviously potential for an unexpected mess. I’d rather be wearing gloves and “not need them” than not be wearing gloves and wishing I had been. I keep a supply of disposable gloves with my sewer supplies. When the dumping process goes as planned it shouldn’t be messy but you’re still dealing with human waste and touching items that have been in contact with it. I’ve seen some big messes at dump stations and wouldn’t touch anything there without gloves.

Also see “Grey and Black Tanks 101” and “6 Steps to Flush RV Grey and Black Tanks