FAQ: Frequently Asked Questions Answer

How Do You Clean Sewage Tanks?

phred Tinseth © 1999-2002 Reproduction permitted

A lengthy process but really easy.

First, dump and flush as normal -- no detergents and PLENTY of water. Once that's done, close dump valve and remove slinky. Then open dump valve and more residue will come out. (Do this at home or somewhere there's no audience.) Use your garden hose to spray the "stuff" at valve and open end of tank. Finally, spray all the poop on the ground and the "brown tea" will dissipate and biodegrade. It's no big deal.

Now comes the easy part. Pour about a quarter cup of ordinary dishwashing detergent in the tank (NON anti-bacterial version), "Dawn" or "Joy" are best. Then pour in about two gallons of water. Drive RV to nearest market. Get about two or three bags of ice cubes and pour them in tank. Then drive to RV park or similar -- make a holiday of it -- (about a two to four-hour drive is adequate). The tank will be about as clean as it ever gets as the ice cubes slosh around and scrub it. Get a site with full hookup. Dump and flush repeatedly. Add about three gallons of water when done. Take a crap (Bio needs something to work on). Add bio per container instructions, then drive home, or wherever your next stop is, to mix things thoroughly.

Routine future dumping should include simple flushing with water and no detergents (unless doing the whole process all over again). You want to keep a residue of the good bio going. (Kind of like a sourdough starter.) Do all this properly, adjusting amount of bio through experience, and you should be trouble free. In my case, as an example: With a 40 gal tank, using "Eco-Save," I put in only one (liquid) capful or one tablespoon of dry version every-other dump (or more) and am odor free and don't have any "floaters" in the tank.

Here's one that screws people up. Often, especially in motor homes, the bathroom, and black tank, are behind the rear axle(s) and the kitchen, and gray tank, in front of the rear axles. So, where does the gray water from shower and bathroom sink go? In most cases, it drains into the Black tank (a cheap and EZ solution for the RV manufacturer). Many RVers don't realize this and wonder why the Black tank fills up so fast. Actually though, it's not a bad situation. More frequent dumping is required, but the bathroom gray water added to the black tank "thins out" the black goop. Reasonable amounts of soap/detergents/shampoo (of the right kind) don't interfere with the bacterial action. RVers with this setup often have very few el-stinko problems if venting and such are OK -- and the RVer knows about it.

Sanidumps.com's Instructions on How to Empty Your RV Holding Tanks

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