I am building a new house in a rural area and it looks like they are going to make us put in a holding tank due to our high water table (which is common in our area). In the spring the water table is 6" to 1' from the surface. Now, it seems ridiculous and extremely expensive to have a giant pumping truck come every few weeks to haul away several thousand gallons of mostly water, rather than processing on site. My thought is, if I could limit the holding tank to black water and deal with the grey water separately that would greatly reduce the frequency of holding tank pumping.
I'm trying to figure out what the best way would be to do this. Our big constraints are that we live in a very cold climate (the average high stays below freezing for over 3 months of the year) and of course the high water table. I've been reading about grey water and it seems like many of the grey water systems for freezing climates deal with the effluent in a similar manner to a conventional septic, with a leach field, which is problematic because a leach field below the frost line would be below the water table for much of the year.
But certain techniques, like the constructed wetland, I'm not sure if it will work because of the freezing temperatures? The plants would not be active for half the year.
One constraint we don't have, which many people looking to do grey water do, is that we have no need to reuse the grey water for irrigation, as our problem is not having enough water, it is having too much.
Does anyone have any ideas for me to look into? Thanks.