How to blast away accumulated crud from RV holding tanks


Ever thought of having your gray and black holding tanks power flushed? “Why would you?” To get out all the nasty crud that accumulates over time, that’s why! And all that crud can cause a lot of problems including faulty sensor readings, not to mention producing foul odors that find their way into your RV (and your nose!).

In this video, see what happens when RVer David Bott’s tanks are flushed out with a whopping force of 4,000 PSI of water pressure. It ain’t pretty!

RELATED VIDEO: Why you should keep your gray tank closed (not just your black tank) when you’re hooked up. Watch the video.

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Colin J. Grant

The problem with pressure washing polyethylene tanks is that it can exceed the hoop strength of the material. High density polyethylene starts to seperate at about 750 psi which means possible leakage between what in effect are hdpe fibers. While it may not drip it could cause a damp surface on the outside causing odour problems.
If you have build up inside the tanks fill with clean warm water and put some draino (sodium hydroxide and calcium hydroxide) it should clean like a plugged pipe. Don’t drain into a septic system.


I keep seeing them putting their gloves hands on the compartment. I sure hope they disinfect everything they touch.

Larry Pousson

What great information, after watching the video on waste tank powering cleaning, I ordered a cleaning nozzle through Amazon. Thank you.


Where can I find the special nozzle he inserted into the tank? Mfgr. name? How much pressure does it take to effectively run the nozzle with a 4 spray pattern? Please advise!


Hmmmm? Gotta wonder if that pressure tip is only cleaning out one side or one corner of the tank. After all you cant see inside the tank and watch it work. Worse yet, what does 4,000 psi do the sensors in the tank? I dont wanna find out the hard way that this wasnt such a good idea. Could be pretty expensive.


I can’t understand the need to use the jetter- you’re not going to drink from those tanks. I use a standard Flush King and I’m satisfied with that…plus I see he’s got a built in tank flusher as well.

Tommy Molnar

For years we’ve been using the swivel wand to clean out our black tank. We don’t do it every time, but usually when we get home we take the time. We just keep ‘swiveling’ until the water runs clear. Wifey sticks it down the toilet. Not sure this high pressure thing does all that much better. We also take advantage of the ‘built in’ cleaning thing that you hook a hose to on the outside of our trailer. So far, so good.
But, I’ve never cleaned out the grey tank and I’m not sure how I WOULD do that . . . We DO keep the grey tank closed.


Can I power flush my tanks with a standard home pressure washer? Is the special nozzle available online?

Mari Harvey

We had this done while in Colorado. Had been having a problem in the sensors in a 5th wheel we recently purchased used. Totally worth it!! Haven’t had any problems since and as long as we rinse well after dumping the tanks they have still been coming back clear when finished.