The Black Water Tank: 9 things every RV owner needs to know

Girl looking at her motor home at sundown

One of the great perks of RV ownership is having your own bathroom wherever you go. There’s only one small price to be paid for this convenience: dumping the waste tanks.

Here's what you need to negotiate your way around this essential but often unpleasant RV task.

1. Don't be afraid to make a dump. 

If there’s one thing that keeps people away from RVing it’s the fear of dumping the holding tanks, but dumping the tanks is as easy as can be. You attach a simple hose, pull a handle, and—whoosh!—your troubles are flushed away. 

2. Understand black vs. gray water. 

Black water is sewer water from the toilet, which in most RVs is held in a separate tank from the gray water (used water from the sinks and shower). When you dump the tanks, first you dump the black tank, then the gray tank.

3. Wash your hands whenever you’ve touched the sewer hose.

We keep Clorox wipes handy when we connect and disconnect the sewer hose, then wash our hands thoroughly when we get inside our trailer.

Some people wear disposable gloves, but that's a bit of overkill - and even if you choose this route, you should wash your hands thoroughly after removing them.

4. Pay attention to what you put into the tanks. 

The black tank should only contain things you’ve previously eaten, easily-dissolved toilet paper, water, and a bit of tank chemical to help things along. Nothing else.

5. Use tank chemicals. 

Often called “sanitizers” or “digestants," these should be added to the black tank every time after it is dumped, along with a gallon or two of water. These chemicals help break down and liquefy the waste, which is what you want for trouble-free tank dumping.

6. Avoid formaldehyde. 

We recommend you choose tank chemicals that don’t use formaldehyde. Formaldehyde kills the beneficial bacteria that help break down the waste. Not only is that counter-productive for you, but it can prevent septic systems from working, which causes problems for campground owners.

Plus, formaldehyde is a known carcinogen. Products labeled “bacterial digestant,” “enzyme based," or “septic safe” are the best choices.

7. Add water. 

Don’t be too skimpy on flushing water from the toilet into the black tank. The tank needs a good ratio of water-to-solids in order to empty properly. Failure to add sufficient water will result in “buildup," and we promise you won’t like that.

8. Skip the special "RV toilet paper." 

This product is sold in RV stores and is more expensive than household variety TP. Sure it works well in RV tanks, but you don't need it to survive on the road. You can easily (and more cost effectively) buy single-ply toilet paper in grocery stores across the country. In a pinch, if you use regular household TP on a trip, it's not going to destroy the tank.

9. Replace the sewer hose at the first sign of trouble. 

To avoid disasters of the worst possible sort (we're kinda glad we don't have a photo to share for this one!), replace the sewer hose at the very first sign of cracking, pinholes, or any sort of wear. People who wait for the hose to fail usually regret their choice.


Photo by Julian Ackroyd on Unsplash

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