Wastewater management

In rural and suburban areas, sewage from homes is usually discharged into a septic tank. To avoid groundwater pollution, septic tanks must be cleaned out every three to four years by a specialised company.

In urban areas, most waterborne wastes from homes, businesses, factories and storm runoff flow through a network of sewer pipes to wastewater treatment plants. Some cities have separate lines for storm water runoff.

When sewage reaches a treatment plant  it may undergo as many as three levels of purification.