Improving Water Quality

Gillian is working closely with fellow MPs, agencies and organisations to improve coastal water quality. Keep up to date with her work below.

For the latest water quality readings from the Chichester Harbour Conservancy - CLICK HERE

For live release data via Southern Water's BeachBouy Scheme - CLICK HERE

Safe to swim? Check for advisories before you swim - CLICK HERE

Chichester Harbour - (Source, Chichester Harbour Conservancy)

There are 3 wastewater treatment plants that discharge directly into the Harbour at Apuldram, Bosham and Thornham. These were upgraded in April 2008 so all treated sewage now receives Ultraviolet (except Thornham) and bacteriological treatment, and some of the nutrients are removed before the effluent is discharged.

In addition, storm discharges from Lavant WWTW can impact the Harbour via the River Lavant, as can Southern Water activity pumping from the surcharged pipes into the River Lavant to take pressure off the wastewater system in upstream villages such as East Dean. Storm discharges from Budds Farm WWTW in Langstone Harbour are also likely to impact to some degree.

Associated with Southern Waters sewage infrastructure, there are several pumping stations and combined sewage overflows, that can also discharge during storm conditions.

What are storm overflows? - (Source, Southern Water)

During heavy rain, local sewer networks can struggle to cope with the amount of water entering pipes and storage tanks.

When they fill up, we use pressure relief valves built into the network – known as storm overflows – to stop homes and businesses from flooding. These overflows release excess water through outfalls into rivers and the sea. Storm overflows are part of the design of the sewers and are regulated by the Environment Agency. They're used in areas where the sewers were built to carry both wastewater from homes and businesses, and rainwater from roofs, gardens and roads.

Did you know?
Storm overflow releases typically occur during periods of heavy rainfall and can be around 95% rainwater.

CSO graphic Southern Water


Attachment Size
CSO FAQs (Southern Water) 735.96 KB


Southern Water response on surface sewage

Below is a response from Ian McAulay, CEO of Southern Water, following Gillian writing to him regarding reports of sewage on the water's surface,

Immediate Investigation

Southern Water launches taskforce to cut storm overflows by 80%

Southern Water is launching a task force this week to cut storm overflows by 80 per cent by 2030.

This is part of the company’s zero tolerance approach to pollution and is part of wider programme of investment to deliver a step change in water quality in the area.

EA response to investigation request

Gillian has received a response to her enquiry from the Environment Agency's Interim Area Director, Nick Gray regarding the recently reported sewerage on the water's surface.


Dear Gillian,