The second photo is what we call a knockdown in America usually on a piece of land that is valuable hence they knock down the house and put up a mansion. Top photo is apparently what they call a knockdown in Thailand . So the top one but bigger.
ok, so your sewage system is akin to an American septic tank and then drain field except your second tank takes the place of the drain field i just read your response so the bottom of the two tanks is open???
Third photo why all the rebar? outdoor kitchen very nice what did that run you? So Im guessing the concrete rings go on top of one another and that is your holding tank for sewage kind of like a big manhole?
Do they put crushed stone under the concrete? I was thinking 12.5 cm of crete and 4 inches of stone -wire mesh? Also in the mountains what do they do large water tank i'm guessing ? For sewer do they have what we would call tile fields (seepage beds)
America ? Or do they install holding tank and pump it out every so often?