Who knew I could get so excited about flushing the gray and black water tanks? Okay, I know it is a bit odd, but as the designated tank flusher I am happy when the “gunk” comes out. While I am diligent about flushing out the black water with the built-in flush system, there was no built-in system for the gray water. When I complained to our RV tech about the smell when driving, he said that the gray water can smell worse than the black.
Mold in the gray water tank
I recently attended a rally seminar about “All things black and gray” and, boy, did I learn a lot! The presenter from Kleen Tank passed around glass bottles of “stuff” that had come out of holding tanks. He did advise, “Don’t open, don’t drop,” while handing it off.
I recognized the black discs that had been coming out of the gray water holding tank and was disgusted when he said it was a massive amount of mold. He also had some discs as hard as metal that he passed around that had “mineralized” with the urine in the black tanks. He said that he finds the gray tank is usually worse than the black, particularly if people have built-in flush systems and had been keeping up with the black tank.
Flush rinser with gate valve and water meter
Best of all, he passed around this flush attachment and water meter. I knew the flush rinser existed, but our hose goes straight down through the bay and there was no way the flush attachment was going to fit. But wait! He showed how the gray and black dump pipe rotates outward and allows the flush rinser to attach! This is what he showed me.
Combined with a water meter, the flush rinser can easily clean out both gray and black water tanks.
The water meter measures how much water is going through a garden hose. It is usually used when watering a garden but it is an exceptional tool for measuring how much water in gallons or liters is going into RV tanks, particularly when flushing. (You can read more about this handy water meter here.)
Warning and Disclaimer:
THE FOLLOWING METHOD IS GENERALLY NOT RECOMMENDED BY RV MANUFACTURERS.
It is not recommended because there can be disastrous results if one walks away from the RV or gets distracted while filling a closed gray water tank or closed black tank with water. Think black water eruption through the toilet into bathroom…
With that disclaimer noted, this was the method taught at the seminar to thoroughly flush out the black water and gray water tanks. This was also the method Kleen Tank used when flushing out our tanks. They had the additional step of a hose inserted into the tanks to pressure wash them along with flushing them out. That pressure wash is what a professional is for!
- IMPORTANT! Double-check the gallon capacity of the holding tanks in the RV specs. If you are like me, it is a good idea to write them down!
- Attach water meter to a garden hose. Do NOT ever use a fresh water hose to flush! Use a backflow preventer to prevent contaminated water going into fresh water faucet. Kleen Tank adds the backflow preventer and water meter at the flush rinser. Others put the preventer and meter at the faucet.
- Attach the flush valve rinser to the sewer pipe opening and sewer hose.
- Pull gray water valve open for a few seconds and close to “lubricate” the sewer hose.
- Dump black water.
- When black tank is empty, follow directions on the flush valve rinser, close the rinser gate valve and fill the tank with water.
- Watching the water meter, fill UNDER the capacity of the tank. I went under by 20 gallons just to be safe.
- Turn off water and pull gate valve. If you can stand to watch, see how much more gunk was in there.
- Repeat with the gray water tank. If your tank was like ours, it was not a pretty sight!
- This flush rinser has a hose rinse setting too, but I found it rather ineffective and figured the gray water going through the sewer hose was rinse enough.
- Add at least two gallons of water to the black tank through the toilet and then treat as normal. A number of people are so happy with this type of flush they don’t add any chemicals, organic or otherwise, to the tanks.
And that’s what you call a royal flush! Happy flushing!