Originally Posted by tjpolsin
This process usually takes me 2 days to finish, as the fresh water tank takes forever to dump. I start in the morning on Saturday. By dinner time I dump the tank. The next day I fill the tank again for a rinse and dump it that afternoon.
Or, if you start with empty gray tanks, you can just leave them open, and run the fresh tank dry by leaving all the faucets open. You're just dumping fresh, sanitized, water. The bleach level is not much higher than in a swimming pool, so is not a waste concern. Won't hurt grass, or anything else, in the area.
Hardest thing is getting the bleach water flushed out of the hot water side, as it takes a lot of repeats to turn over the 6 gal or so in the heater. I've found it best to pull the heater drain plug after sanitizing, let it drain, then carry on with a final flush of the system.