I am building a house that is a vacation rental and by necessity, it will be occasionally filled with more people than the septic system is designed for. I am trying to find out what I can do to minimize the problem. It has a 4 bedroom septic but may be filled with 12-14 people and it is very hard to control what short term renters will do.
I was going to go with 1.3 gallon toilets and of course code compliant shower heads. There will be only 1 bath tub.
One thought was to run the shower and bathroom sink drains separately and use that for gray water irrigation (if allowed). But I've heard that you need some amount of "clean" water for everything to function correctly. Certainly some of the water could go to septic and some to irrigation.
Obviously no garbage disposal. Frequent cleaning out (annually?). This is an area with a 12 week peak season so it won't be filled a lot of the time.