There are three types of sewerage systems:
- foul sewers – carry waste water, for example waste from toilets and from trade premises to the wastewater treatment works
- surface water, or storm sewers – carry rainwater from roofs, paved areas, pavements and roads and generally flow into streams, rivers or watercourses
- combined sewers – this is a single pipe system which carries both wastewater and surface water to wastewater treatment works, these are often found in older town centre systems and are no longer designed or constructed
It is an offence to discharge foul sewage to a sewer designated for surface water or surface water into a sewer designated for foul sewage.
All new sewerage systems should be designed on separate foul and surface water (storm sewers) systems.
Sewers carry both domestic and industrial waste water to wastewater treatment works, where it is treated and safely disposed of to meet legal requirements.
After treatment, the cleaned water goes to a nearby watercourse or the sea and must meet with the legal conditions set by the Northern Ireland Environment Agency (NIEA).
The sewage sludge which is produced as a by-product of the sewage treatment process is further treated and disposed off through incineration and landfill.
If you have a problem about sewage, contact NI Water:
- telephone: Waterline 0345 744 0088
- Northern Ireland Water
To report a water leak, go to:
Responsibility for sewerage pipes
The pipework which makes up the sewerage system can be categorised in three ways:
- public sewers – Northern Ireland Water owns, operates and is responsible for maintaining a network of over 13,000 kilometres of public sewers which are designed to take away waste and rain water to the wastewater treatment works
- drains - a drain is a pipe which carries waste water (from sinks, baths and toilets) and trade waste from one property to a sewer; responsibility for the drain within the boundary of the property lies with the owner of the property
- private sewers - a private sewer is a pipe which collects and carriers waste and waste water from several properties; a private sewer may connect to a public sewer or private wastewater treatment works; responsibility for a private sewer lies jointly with the owners of the properties which it serves
Access to sewerage pipework
Most sewers are under roads or in public open places. Some sewers run through private gardens. NI Water has a right of access for maintenance.
Work on public roads
Many watermains and sewers are laid in public roads and footpaths. Sometimes NI Water will need to do work on a sewer.
Work on private land
Sometimes NI Water needs to go onto your property to lay new services, maintain existing services or inspect your water or sewerage system. They'll contact you before they enter your land.
Getting connected to the public water supply or sewerage system
NI Water is responsible for the provision of services associated with all aspects of development including first time service appraisal, diversions, extensions to the watermain distribution system and sewer network, watermains in new development and adoption of sewerage systems.
To read more about connecting a new property to the public water system, go to:
Customer Care and Critical Care Register
NI Water provides essential services for all customers throughout Northern Ireland. For older consumers, those who have a serious medical condition or need extra help for any other reason.
You need to join the Customer Care Register to get the extra free services you or anyone in your household would like to receive: