By Nanci Dixon
I had a chance to attend a seminar on all things black and gray tanks and learned a new dump technique. After all these years of RVing, I had never heard of or thought about this sensible tip to keep your sewer hose clean.
Here is a quick, easy tip to help keep your sewer hose clean
When planning to dump the black tank, first pull the gray water valve for about three seconds, then close it to allow the gray water to run through the sewer hose. The few seconds of water running through the hose will wet it down and coat the inside. This helps prevent debris, particularly from the black tank, from sticking in the crevices and around curves.
Thinking of all the places gunk can collect, particularly around the wires, makes this technique make a whole lot of sense. This technique also allows you to check for leaks before dumping the black tank.
Pulling the gray water valve when done further rinses out the sewer hose. Listen for that welcome whoosh of a full tank swirling around, scrubbing the insides of the tank, and fully emptying.
Did you know about this trick to keeping your sewer hose clean?
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The 2 sewer hose tips are just “common sense”. But “common sense” is not so “common” in todays world.
One more tip for those that leave their grey valve open during their stay. Close the grey valve a day or two before your scheduled departure date so that you can use the accumulated grey water to rinse your sewer hose after you dump your black tank. Silicone grease on the hose seals will not only extend their life and seal ability but make disconnecting a bit easier.
We never leave the grey valve open. Plus, if the grey tank is full a day or so before we leave, I just empty it to get it to a usable point for the rest of the stay.
And if the black tank is not at least half full, I run water to get it to that point. The more water in the tanks, the better they flush.
Yes, been doing this for about 20 yrs.
Thank you for the suggestion, Nanci! Have a great day, a grand 2026, and safe travels!
We bought our first (of 5) RV trailers in 2008. The guy showing us our first walk-through told us about this, and we have used this procedure ever since. However, there is always room for learning something new.
I usually open the gray tank first to check for leaks and a secure connection. Guess that’s why my hose is so clean!
I’ve always cracked the gray tank open before I dumped the black because if I have a leak I’d rather catch it with gray water than the black then I open the gray to dump it, gray water doesn’t need to be cleaned up like the black! Yuck!
I haven’t been “prewetting” my sewer hose but will start on my next dump. But what I do is dump my black tank first, close my add-on “no-surprise” valve, then open the grey valve to put grey water into my black tank but only for perhaps 10 seconds, then close the grey valve, open the no-surprise valve and empty the black tank. Repeat this process flushing the black tank with grey tank water 2-3 times, then finish draining the grey tank. I’ve been using this process for over 20 years and I believe it eliminates, or at least reduces, black tank draining issues.
“…and coat the inside.” lol Easier method is dump when full…black then grey. For purists refill waste tanks and dump again