Does my black tank sprayer really get my tank clean?

Sort of. It’s better than nothing, we’ll certainly say.

Almost every RV on the market in the last 20 years came with a spray system for the black holding tank. Some high-end motor coaches also feature these for their gray tank, but that setup is pretty rare.

In a normal RV, you connect a garden-style hose (NEVER the same one you use for freshwater supply!) to an inlet near your waste tanks. This forces water through a nozzle — sometimes stationary; in other cases, it spins — and into your black tank. The pressure or PSI from this nozzle is a step up from the hose pressure (due to the reduction in nozzle size vs. supply hose size) of about 100-150 PSI.

The spray pattern tends to be pretty consistent and may get most of the tank’s interior surfaces. Is it enough to thoroughly wash the inside of your tank clean? No, but it does a good job of keeping things moving along, especially if you use it during emptying of your black tank.

The only true way to get your black (and gray!) tank thoroughly cleaned is to use a professional RV tank cleaning service. They use water pressure at 1500 PSI on up, or 10-15 times what your onboard spray system does.