Wastewater, commonly referred to as sewage, is a mixture of water from domestic sources such as baths, sinks, toilets and washing machines, and from industrial pollution and rainwater run-off from roofs, roads and other hard-surfaced areas.
There are different systems for treating wastewater.
- Surface-water sewers take rainwater run-off from roads, yards and roofs, often releasing it without treatment back into the environment.
- Combined sewers carry domestic sewage, trade waste and some rainwater run-off to wastewater treatment works (WwTWs) such as the ones at Brechin and Montrose. This water is then released back into the environment.
- Individual properties that are not served by WwTWs have their own smaller individual systems such as septic tanks with soakaways or secondary treatment systems, all of which can release wastewater to the land.
Scottish Water collects and treats wastewater, while smaller treatment systems for individual properties are the responsibility of each owner.
Scottish Water has a capital investment programme known as Quality and Standards, to maintain and upgrade WwTWs across Scotland. Local authorities are responsible for drainage systems to deal with run-off from roads.
All systems which release wastewater into water or onto land are now licensed by SEPA under a new regulatory regime, the Controlled Activities Regulations (CAR) April 2006, as part of the Water Framework Directive.