Boy, here’s a misperception: Should you leave your RV’s gray tank valves open all the time? Well, nearly every RVer we talk too — especially the big fifth wheelers and motorcoachers — say “yes.” Well, here’s what we think.
Your RV’s waste system is meant to hold waste until you have a chance to flush it out. It’s a complicated system of piping and holding tanks. Lots of twists and turns and tanks that are normally squarish with corners and walls that can catch waste. What’s this all mean? Well, letting waste — in this case, gray water which is normally from your galley sink and bathroom shower, sink and/or bathtub — slowly find its way through the waste system and then out into the ground system probably is asking for trouble.
As that waste and water slowly move along to the outside, there are plenty of places where solids can stop and catch — the bottom and corners of the gray holding tank and within the pipes as they lay nearly horizontal in your RV’s belly pan.
The best solution is to use your RV’s waste system just as it was designed: Let waste build up in your tanks until they are at least 75% (or more) full. Then, open the gates (black first, then gray) and let gravity and the resulting “tornadic” effect of that evacuating liquid pull all of the solids through your RV’s waste system.
Can you leave the gray tank’s valve(s) open all the time? Yes. But don’t be surprised if you eventually experience problems like slow draining and bad odors (that’s bacteria growing on solids that are — literally — hanging around). We’ve seen it time and time again: We do a high
We’ve seen it time and time again: We do a high-pressure cleaning and then two or even three backflushes that continue to pull out solids that never get a chance to leave your waste system. A smart RVer knows to let the system do the job it was designed to do — act as a holding tank until it is emptied when full.