Seaham heats homes with flooded coal-mine water tapped at an old treatment works

A mine water heating system has gone live in Seaham, County Durham: an ultra-low carbon district heat network now supplies heat to about 50 properties in the Seaham Garden Village development, and is to extend to 750 homes as the 1,500-home complex is built out over the next ten years. The project is a collaboration between Durham County Council, the Mining Remediation Authority, housing association Karbon Homes and energy company Vital Energi.

The trick is that the heat source and the capture point already existed. Mine water temperatures naturally range from 10 to 20C all year round due to deep underground geothermal processes, according to the Mining Remediation Authority. The Seaham network taps the Dawdon minewater treatment works, which was originally set up to treat local minewater and prevent the contamination of about 30,000 people's drinking water. The heat that previously dissipated into the atmosphere as part of that treatment process is now used to heat properties instead.

The arrangement is not unique to Seaham: similar networks are already running in places such as Gateshead, and Durham County Council said it is exploring whether comparable schemes could be set up elsewhere in the county. Councillor Kyle Genner said the authority hoped to create more as long as they were 'financially viable', adding that sites should be found as they become more viable and the technology evolves. Vital Energi's Kieran Walsh framed the core benefit plainly: 'You are obtaining heat from a waste heat source.'

Abandoned coalfields hold water at a steady 10-20C year round, so the heat source needed no new deep drilling — the geology does the storage.

Dawdon works was already pumping minewater daily to protect 30,000 people's drinking water — heat capture attached to an existing flow.

The demand side came with the site: the 1,500-home Seaham Garden Village next door gave the network an anchor load, starting at 50 properties and growing to 750.

A four-way partnership split the roles: council, Mining Remediation Authority, housing association Karbon Homes, contractor Vital Energi.

Remediation infrastructure built for one hazard can seed the next system: the plant that kept drinking water clean now supplies heat, and every litre it pumps pays twice.

The network is live as of October 2026, supplying about 50 homes, with extension to 750 properties planned as the 1,500-home complex is built over the next decade. Durham County Council is exploring similar schemes elsewhere, noting that mine-water networks already operate in Gateshead; further sites depend on financial viability as the technology matures.