Erillisviemäriin

Erillisviemäriin refers to a separate sewer system for wastewater and stormwater, distinct from combined sewer systems. In a combined sewer system, both domestic sewage and rainwater are collected and transported through the same pipes. In contrast, an erillisviemäriin system consists of two separate networks: one for sanitary sewage (wastewater from homes and businesses) and another for stormwater runoff (rainwater and snowmelt from surfaces like roofs, streets, and yards).

The primary advantage of an erillisviemäriin system is the prevention of combined sewer overflows (CSOs). During heavy rainfall, combined systems can become overwhelmed, leading to untreated sewage and stormwater being discharged directly into receiving waters. Separate systems ensure that wastewater is always treated at a treatment plant, even during storms, as the sewage pipes are not overloaded by rainwater. This significantly improves the water quality of rivers, lakes, and coastal areas.

Implementing an erillisviemäriin system requires a more extensive and costly infrastructure compared to combined systems, involving the construction and maintenance of two separate pipe networks. However, the long-term environmental benefits, particularly in reducing water pollution and protecting aquatic ecosystems, are substantial. Many older urban areas were originally built with combined sewers, and the transition to separate systems, or the construction of new developments with separate systems, is a common practice in modern urban planning and environmental management.