The gray and black holding tanks in RVs can get a bit dirty over time, so it is generally recommended to get them professionally cleaned out every year or so, depending on usage. We also have had issues with odors and sensor mis-reads, so thought getting them cleaned might help.

While in the LA area, we engaged All Pro Water-Flow So Cal to flush our tanks; we found them via an ad on the campground map. I can’t whole-heartedly recommend them, though, as they didn’t solve the sensor mis-reads. I’m not sure if the issue was something other than dirty tanks, or perhaps they didn’t do a good enough job. I’ll try to get the sensors looked at during an upcoming service.

The mechanism is simple enough: a hose connects to a pressure washer, with another hose with spray heads that is inserted into each of the tanks in turn, and manipulated to move around inside the tanks, washing their internal surfaces: