Use gray to flush black

DrewE wrote:
The question wasn't about using gray water to flush out the black tank, but using it to flush the toilet. I think I've read here of one or two people who have rigged something up to do that. It's basically just installing a suitable pump and running some water lines to it. Probably having a selector valve to let either the fresh or gray water be used for flushing (and a check valve for the fresh water line to prevent any possible cross-contamination from the gray water) would be a decent idea in case one needs to go potty before anyone has taken a shower or washed the dishes.

Note that the gray water can get pretty stinky over time. For the amount of fresh water that would be saved, I don't think I would bother. RV toilets don't need a lot of water to flush.

I have a grey water flushing system installed in my 5th. I have two grey water tanks and I only flush using the shower and bathroom sink water so the water is pretty clean. I can select fresh or gray water for flushing. I have a separate pump and filter for the grey side. Our problem was that the grey shower water tank would fill up 1st while the fresh water tank would become empty 1st. The grey water system creates a perfect tank balance and we are not afraid to use adequate amounts of water for flushing. I use black tank chemicals but put them into the grey tank where they get dispensed over time into the black tank. The system works well and extends our stay by several days.