What is an example of low cost onsite sewage disposal system

I guess Septic tanks, chemical toilets and composting pits

Septic tanks , composing pits and chemical toilets

To improve sanitation, low cost onsite sewage disposal systems are being encouraged. Examples are septic tanks, chemical toilets, composting pits.

Septic tanks are suitable for places where there is no sewerage system, for hospitals, isolated buildings or a cluster of 4 to 5 houses.

Some organisations offer hygienic on-site human waste disposal technology. These toilets do not require scavenging. Excreta from the toilet seats flow through covered drains into a biogas plant. The biogas produced is used as a source of energy. (Composting pits).

A chemical toilet collects human excreta in a holding tank and uses chemicals to minimize odors. These toilets are usually, but not always, self-contained and movable. A chemical toilet is structured around a relatively small tank, which needs to be emptied frequently.

helicase, i think thats it

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.