A method for disposing of
sewerage in
rural areas with no
drains.
Waste water flows into one or more big tanks and the solid stuff sinks to the bottom. Bacteria eat away at the waste and margianaly cleaner water then flows out to pipes with little holes in them which run under your garden keeping your lawn nice and green even at the height of summer.
If you kill the bacteria eg. with bleach, it will start to smell.