Engineering is a series of tradeoffs. Housebuilding is no exception. I ended up choosing to have a bathroom and a second kitchen in the basement although with other considerations it meant that the waste effluent will have to go uphill to the leach field. To avoid having to use a "macerator" type pump that grinds and pumps solids (poor MTBF, i.e. trouble prone) we are placing a conventional septic tank downslope of the walkout basement but its output will not go directly to a leach field it will be pumped uphill by a liquid handling pump to the level of the septic tank serving the ground floor and upstairs.

Anyone out there have experience in systems that have to do things like this? Do you plumb the output of the pump to a "T" at the output of the "main tank?" If it weren't for a "stiring up the solids" issue, I'd be leaning toward sending the pump output to the main tank. My previous reading on septic systems gave me the impression that you wanted the last chamber in the system to be fairly undisturbed and stay full with its over flow being nearly clear water, solids having settled out. Pumping a batch up from the lower tank would certainly stirr things up.

Perhaps I should consider one extra chamber in the lower tank. This would fill from natural gravity flow from what is ordinarily the last chamber and not contain anything that wouldn't have ordinarily gone to the leach field. Then it could be pumped as a batch to the leach field without puting anything in the leach fiield that it wouldn't have already had. (some of this started sounding like a "horse with no name")

Sure don't wan't to cause stuff to go to the leach field that it shouldn't get. I would like to have enough reserve capacity in the lower tank such that it would not "back up" during power outages of several hours or maybe a couple days if that is practical. In an extended outage I will, of course, fire up a generator to "recharge" the frige and freezer, get weather reports on sat TV, and such so electricity to run the pump will be available.

Ideas?

Patrick