Originally Posted by Danjo
I think thatís because the kitchen is commonly plumbed to the grey tank when it is considered black water by the EPA
I think it's more the fact that there are so many recreational vehicles these days that it's the soap and such in the grey water. Otherwise they could just classify the sink water as black water which is already prohibited. The problem with that is that RV manufacturers or DIYers would soon be using separate tanks for sink water.
For instance, our design has a separate holding tank for the kitchen and bathroom sinks and a second tank for the laundry machine and shower. That tank will then be filtered to yet another tank which we've designated as the reclaimed tank that will be used for shower, laundry, and toilet flushing.
A 30-45 gallong reclaimed tank holding water from the shower/laundry holding tank will be refilled via screen, cartridge, and then reverse osmosis filtering with a final step of UV sterilization. Our Splendid all in one washing machine (which we found at Habitat for Humanity Restore for $100 in perfect working condition) only uses 15 gallons on the highest use settings and about 10 on normal (for a full load) so even a 30 gallon reclaimed tank would usually leave 20 gallons for showers and the RO is supposed to be able to refill that 30 gallons at a 400 gal/day rate (I'll be happy at less than 100).
The whole purpose is to make our 200 gallon fresh supply last 30 days or more.