A £350,000 scheme to improve river water quality in the Tees Valley and County Durham is due to begin.
The work, by Northumbrian Water, will upgrade and screen four sewer overflows in the Sedgefield area.
These discharge waste water into watercourses during very heavy rainfall to protect properties and land from the risk of flooding.
The River Tees, River Skerne, Shotton Beck and Redcar Beck will benefit from the work, which starts on Monday.
It is expected to last three months, and during that time Northumbrian Water may need to access manholes located in residents' drives or gardens.