Toilet & Black Tank Care Made Simple

How your trailer's toilet works

At home, every flush disappears into a city sewer or a septic system. Your trailer has no pipe to the city. The toilet drops straight down into a holding tank under the floor, called the black tank, and everything stays there until the tank is emptied.

That one difference explains every rule on this page. A house toilet forgives almost anything. A holding tank works great too, it just needs a little teamwork.

(Your sinks and shower drain into a second tank, the gray tank. It mostly takes care of itself.)

The clog nobody warns you about

RVers call it the pyramid plug. It is what happens when the black tank valve gets left open.

With the valve open, liquid quietly drains away but solids stay behind. They stack up right under the toilet, dry out, and harden. Given enough time, the pile climbs until nothing can get past it. Water starts backing up toward the bowl, and the fix goes from free to expensive.

With the valve closed, everything sits underwater, where it softens and breaks down. On dump day the full tank rushes out all at once and takes everything with it. The water does the cleaning. That is also why you wait until the tank is at least two-thirds full before opening the valve.

Think one is starting? The signs are a slow-draining flush, a gauge that will not move, or a smell that will not quit. Close the valve, fill the tank most of the way by flushing clean water, add a double dose of treatment, and let it soak overnight or up to two days. Then empty it. One or two rounds of soak-and-dump clears most early pyramids.

Never pour drain cleaner into the toilet. Products like Drano or bleach destroy the rubber seals and the plastic valve, and they turn a free fix into a repair. If two soak-and-dump rounds do not clear it, stop and open a support request. Earlier is always cheaper, and nothing you tell us will surprise us.

If the bowl will not hold water

A little water should always sit in the bottom of the bowl. That water is the lid between your bathroom and the tank, so when it drains away, the smell comes up.

At the bottom of the bowl is a rubber seal that slides open when you press the pedal and closes again when you let go. Water only leaks out when something keeps that seal from closing.

Try this first, because it fixes most cases:

1. Look in the bowl for paper or debris sitting on the seal. That is usually the whole problem.
2. Hold the pedal down and let clean water run for several seconds to rinse the seal, then let the pedal come all the way back up.
3. Fill the bowl and check it an hour later.

Often the seal is not worn at all, it simply is not seated. A scrap of paper holds it open a hair and the water creeps out. Rinsing it lets it close properly again.

If the bowl still empties after a couple of tries, the seal is worn or torn and needs replacing. That one is our job, not yours. Open a support request and we will come take care of it. Please do not force the pedal or pour anything into the bowl to try to seal it, because that usually turns a small part into a bigger repair.

Emptying the tank, step by step

If your trailer is connected to a sewer hookup and you empty it yourself, this is the whole job:

1. Wait until the black tank is at least two-thirds full. A fuller tank flushes out harder and cleaner. If you need to empty early, top the tank up first by flushing extra water for a few minutes.
2. Pull the black valve (the bigger handle) all the way. Let it run until it goes quiet, then close it.
3. Pull the gray valve. The used sink and shower water follows the black water out and rinses the hose clean.
4. Close up, then reset the tank. Always close the black valve. Close the gray one too, unless yours is meant to stay open (see below). Then put three or four bowls of clean water down the toilet with a treatment. That fresh water layer is what makes the next week easy.

If your gray valve is left open on purpose

On a lot of our longer-term setups the gray valve is left open, so sink and shower water drains away on its own. If that is how yours is set up, leave it that way. It is normal and it is fine.

The important part: that exception is only ever for the gray valve. The black valve still stays closed. Everything on this page about a valve being left open is about the black tank.

Two things to keep in mind while the gray stays open:

• You give up the free hose rinse from step 3. Every week or two, close the gray valve for a day so the tank fills, then dump the black tank and open the gray right after. That gives the hose a good flush.
• If a smell ever comes up the shower or sink drain, close the gray valve for a day and pour a dose of treatment down the drain.

If a service empties the tank for you instead, the habits still carry the day: black valve closed, plenty of water, the right paper, and a treatment after each service.