Densely populated urban areas, indi-vidual houses, residential enclaves and apartment blocks are confronted with special problems related to wastewater collection and treatment, such as:
As a result, most urban real estate with on-site facilities has only a small septic tank for each household. In the majority of cases, this solution does not meet governmental guide-lines on wastewater effluent.
The effluent from insufficient or faul-ty septic tanks contaminates ground-water or even bore wells that are used for household water supply. This is one of the reasons why most of the bore wells in big cities are highly contaminated with e. coli.