Contamination of drinking water sources by sewage can occur from raw sewage overflow, septic tanks, leaking sewer lines, land application of sludge and partially treated waste water. Sewage itself is a complex mixture and can contain many types of contaminants.
Septic Tank Cleaning
Septic tanks contaminate 1% of the nation’s usable aquifers. Septic tanks are enclosures that store and process wastes where no sewer system exists, such as in rural areas or on boats. Treatment of waste in septic tanks occurs by bacterial decomposition. The resulting material is called sludge. Large portions of the population are still served by septic systems as opposed to public waste treatment facilities. Contamination of water from septic tanks occurs under various conditions:
Poor placement of septic leachfields can feed partially treated waste water into a drinking water source. Leachfields are part of the septic system for land based tanks and include an area where waste water percolates through soil as part of the treatment process.
Badly constructed percolation systems may allow water to escape without proper treatment.
System failure can result in clogging and overflow to land or surface water.
High density placement of tanks, as in suburban areas, can result in regions containing very high concentrations of waste water. This water may seep to the land surface, run-off into surface water or flow directly into the water table.