Originally Posted by
mikenot
“ Those drains (brown and grey water from the septic tanks and grease tanks respectively) will both join the storm water drain to the stream. Several questions here. Can we do this?”
well, the brown water from the septics certainly should not ! That should drain out into a leach field / soakaway where it undergoes further biological treatment (well away from a veggie garden). Ideally the grey water wouldn’t either , but this is Thailand. There are plenty of buildings discharging grey water ( with and without grease traps) into canals, storm drains and even straight on to the street ( which is what our rental house did until I at least diverted the grey water into a gravel filled soak away ).
If you have the space and the slope of the land allows it, best to have both run into a leach field, and then soak through the soil and plants into the stream eventually, by which time it would hopefully be harmless.