Fecal coliforms are a specific group of bacteria, largely used as indicators of fecal contamination in soil surrounding on-site sanitation systems. While in freshwater and marine habitats, enterococci, a different type of bacterium, are frequently thought to be more accurate markers of fecal pollution.

Whereas, the chemicals that on-site sanitation systems may release into nearby soils include pharmaceutical discharge possibly containing traces of antibiotics, hormones, and many other compounds, as well as agricultural soil nutrients like urea and phosphorous. Moreover, effluent or wastewater may also contain other materials including industrial chemicals, heavy metals, and cleaning agents, contingent on the utilization of on-site sanitation systems in commercial and residential contexts. Cleaning agents may include abrasives, degreasers, detergents, acids, and a number of other compounds & formulations.