Draining the Rain in Midlothian - £6m Project to Improve Water Quality

“Working with the Scottish Environment Protection Agency we have committed to delivering a project that will make a significant, positive difference to the water environment and ensure water quality levels improve”

Ethan Gillies Denning
Senior Project Manager Scottish Water

Scottish Water is to begin work on a £6million project to improve water quality and reduce sewer related debris entering a Midlothian water course.

Part of the publicly owned utility’s Improving Urban Waters programme, a new storm overflow chamber and storm water attenuation tank will be constructed in Bilston Park.

A powered screen will filter out sewer related debris bigger than 6mm before discharging into the Bilston Burn, while a 750 cubic metre tank – a third of the size of an Olympic swimming pool – will reduce spills during heavy rain by ensuring the sewer network is not overwhelmed.

Senior Scottish Water Project Manager Ethan Gillies Denning said: “The existing infrastructure has been causing issues for some time.

“Customers have told us about problems with spills and sewer related debris during heavy rain and subsequent testing confirmed the burn wasn’t meeting our regulatory standards.

“Working with the Scottish Environment Protection Agency we have committed to delivering a project that will make a significant, positive difference to the water environment and ensure water quality levels improve.

“The majority of the work will be carried out within the park itself so we are confident there shouldn’t be too much disruption for the local community.

“We will work with all those affected to deliver the project as quickly and painlessly as possible and would like to thank them for their patience and understanding.”

From Monday 9 February 2026, the project site compound will be set up on land just north of the Bilston Burn, with the new overflow chamber and storm tank being installed under the grassy area on the other side of the burn.

Some parking restrictions will be required on Caerketton Avenue to allow heavy machinery and deliveries access to the site. 

Work on the A701 under temporary traffic lights will also be required from around the middle of March for approximately seven weeks.

The project is part of Scottish Water's Improving Urban Waters programme, an additional £500million package of investment to improve the environment and make it more enjoyable for customers to explore their local area.

Working closely with the Scottish Environment Protection Agency (SEPA) Scottish Water has identified priority storm overflows for improvement or replacement for water quality or aesthetic – sewer related debris – reasons.

Under the banner ‘Draining the Rain, Enhancing the Environment’ the investment will help prevent sewer related debris such as wet wipes from entering the environment during periods of rainfall.

The project is being delivered by Scottish Water’s alliance partner, Caledonia Water Alliance and is expected to be completed by spring 2027.