The Valterra Flush King Back Flush Valve

Looking for a “pro tip” to get your RV’s holding tanks clean? Use the Valterra Flush King Back Flush Valve on a regular basis and you’ll experience healthier, cleaner tanks with minimal odors.

Valterra Flush King Back Flush ValveDoubtless you have some questions about your tanks and how to flush them out. Here’s some of the most common ones we hear:

Q. My RV has a tank flushing system. Why do I need something else?
A. The in-tank rinsing system in your black holding tank sprays in set pattern, either through a single spray head or a rotating array of nozzles. While it’s a good system, it can take a long time to fill your holding tank to thoroughly flush it out. Plus, it’s only in your RV’s black tank. We do recommend, however, that you turn the rinsing system on while you are emptying the black tank. The added turbulence and flow of water is helpful.

Q. I use the tank flushing system after I empty the tank. Isn’t that enough?
A. The PSI of your in-tank rinsing system is 100 PSI to 150 PSI, since it comes from the RV park’s pressurized water supply (usually 40 to 80 PSI). Reduction of pipe size and the nozzle spray head increases that pressure a bit, but the flow rate is reduced. It can take a long time (a half hour or more) to fill up your black holding tank for rinsing. Plus, again, there’s no similar system in your gray holding tanks.

Yes, your RV’s black tank has a rinsing system built in. But it rinses, not flushes, and there’s no similar mechanism for your gray holding tanks.

So what’s the solution?

We use as a part of our professional holding tank cleaning service — and recommend to our customers — the Valterra Flush King Back Flush Valve. It’s the best way to quickly fill your holding tanks so that they can be thoroughly flushed out. Here’s how to do it:

  1. Empty each of your holding tanks as you normally would.
  2. Make sure that the holding tank release valves are closed.
  3. Disconnect your flexible sewer hose from the attachment on your RV, in your waste system bay, or where the flexible hose attaches to your main pipe fitting.
  4. Attach the Flush King to that same main pipe fitting.
  5. Attach your flexible sewer hose to the other end of the Flush King.
  6. Attach a water hose from the pressurized water tap at your site to the fitting on the Flush King. Never use the same hose you use for your potable water supply.
  7. Close the valve on the Flush King, preventing any water from your RV to travel down your flexible sewer hose.
  8. Starting with your black tank, pull the release valve for that tank (so it is open).
  9. Turn on the water supply knob on the Flush King. Pressured water should now be rushing into your black holding tank.
  10. Depending on the pressure of the RV park water and the capacity of your holding tank, the tank should fill in anywhere from a minute or so to around three or four minutes. If your sensors work, you (or someone inside the RV) can monitor them to indicate the tank is full. You may wish to get a water meter and attach that to your pressurized water supply hose to monitor how much water is going into your holding tanks (that’s what we do).
  11. When the holding tank is 90% full (be careful not to go over the tank’s maximum capacity), stop the flow of water into your holding tank by turning off the knob on the Flush King.
  12. Open up the release valve on the Flush King (on the flexible sewer hose side). Water will rush out, down the flexible sewer hose and into the the RV parks sewage system or tank). Watch to see how clear the water is (we bet you’ll see quite a bit of waste).
  13. Repeat steps 7 through 12 until the water from your black tank runs clear.
  14. Repeat steps 7 through 13 for the gray holding tanks.

Get the Valterra Flush King and use it to keep your tanks clean and working properly.

Can we ask you a favor?

We normally have the Valterra Flush King Back Flush Valve for sale at our vendor booth when we attend a rally and always have one or two for sale on our service truck if anyone wanted to buy one at the time of service. You can certainly purchase them at some camping store locations like Camping World as well.

If you are interested, however, in ordering a Valterra Flush King online from, we ask that you click on this link. Purchasing the Valterra Flush King via this link won’t cost you anything, but Kleen Tank earns a very small commission from your purchase. Thank you!

Jim Tome, Owner

Jim Tome, Owner

Hi, I'm Jim Tome and, along with my wife, Debbie, the owners of Kleen Tank LLC, the national leader in RV holding tank cleaning service. We've been RVers like you since 2004 and have traveled all over the U.S. in our Airstream travel trailer. We started the business about twelve years ago and have cleaned tens of thousands holding tanks in thousands of RVs. From tiny weekend travel trailers to monstrous fifth wheels to luxurious motorhomes, I've seen just about every situation there is with RV holding tanks and waste systems. I hope you enjoy our articles; I try to post at least one per week and we've got a great library of them to cover just about every problem. Enjoy!


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