Our work around Langstone Harbour

Langstone Harbour is popular among water sports enthusiasts. Although not a designated bathing water, we work hard to help maintain the environment around the harbour – including investment, regular public updates, beach patrols and water quality checks.

Today, the surrounding bathing waters are all rated ‘excellent’ by the Environment Agency. Read on to learn how we’re protecting water quality in Langstone Harbour.

Managing the impact of wastewater

During a downpour, rainwater is channeled into sewers and released out to sea to prevent flooding on land. Like the overflow on a bath, this stops water collecting in our streets, flooding our network and forcing its way up into people’s homes.

To prevent flooding in Portsmouth and Havant, we’re permitted by the Environment Agency to release stormwater into Langstone Harbour. However, we’re careful to make sure we meet our statutory duties to the environment.

Contrary to popular belief, stormwater releases are not ‘raw sewage’. They’re made up of wastewater – primarily from washing machines, showers and dishwashers – and are heavily diluted by rain. Before releasing stormwater into the harbour, we screen it and remove solids first – to prevent items like wet wipes ending up on beaches.

Over recent years, we’ve devoted millions of pounds to further reducing the impact of stormwater releases on the harbour. Following investments of £20 million in Portsmouth and £14 million in Fort Cumberland, all the local beaches in Havant have been recognized as ‘excellent’ by the Environment Agency – evidence of reliable bathing water quality, despite permitted stormwater releases.

Keeping the public informed

Although not a bathing water, Langstone Harbour is popular with water sports enthusiasts. To help members of the public make informed decisions about whether to go into the water, we’ve chosen to announce when we release stormwater into the harbour.

We provide notifications to Langstone Harbour Board and other local groups. In addition, we’re now piloting our Beachbuoy system (southernwater.co.uk/beachbuoy) that allows people to check for recent releases via a map on our website. The latest version of Beachbuoy also allows people to sign up for email notifications so they can stay up-to-date on-the-go. This is a trial and we're continuing to assess community feedback.

Boots on the ground – beach patrols

Along with the Environment Agency, we patrol the beaches around Langstone Harbour to investigate reports of debris on the beach.

Our misconnection investigations team conducts a walkover on Hayling Island in July. 

On 18 July 2019, we were told sewage had been sighted on the beach, which was gratefully received, and we responded by launching a patrol. Although our records showed no release had been made from our network, a member of our Misconnections team visited the beach. Interviewed at the scene, he said:

“We’re here off the back of a report from a member of the public that there was sewage on the beach. We’ve walked roughly half a mile one way and half a mile the other way to look for the reported sewage spill. There was absolutely nothing, apart from the odd bit of beach debris.”

As well as our patrol, the Environment Agency carried out its own visit. Neither party found any signs of sewage-related waste. However, we did spot items that may have been left by beachgoers or washed up on the shore – including litter and plastic pollution.

Monitoring water quality

As Langstone Harbour is not a designated bathing water, the Environment Agency does not measure the water quality. However, our models suggests it meets ‘excellent’ standards 95% of the time – in line with the surrounding bathing waters. Samuel Underwood, Southern Water’s stakeholder manager for Hampshire explains:

While water quality in Langstone Harbour is not measured by the Environment Agency, the modelling we have carried out suggests it is at the bathing water ‘excellent’ standard 95% of the time. Meanwhile, all local bathing waters are deemed to have ‘excellent’ bathing water quality by the Environment Agency, some for as many as 29 years.”

We welcome independent testing and have suggested Portsmouth City Council and Havant Borough Council carry out their own tests and publish the results for local water users to see. This approach has been taken at Chichester Harbour and gives the public independent assurance of the quality of the water.

Our next step – Zero Flooding in Havant

Water quality is affected by a range of factors, including what people put down their sinks and toilets. If people put the wrong things down their drains – like wet wipes and grease – they can stick together and form fatbergs that clog sewers. This can force sewage to overflow through manholes and be washed into rivers and out to sea.

To protect water quality around Havant, we will soon launch our Zero Flooding campaign in the area. As well as deploying teams to physically unblock pipes and drains, we’ll be communicating with residents to help them do their bit in keeping our sewers flowing – and our water quality high.


During a downpour, releases of stormwater into Langstone Harbour are essential to protect local residents’ homes and businesses from flooding. Yet, we understand how important the harbour is to water users too. That’s why we work hard to keep the water quality high and minimise the impact of our permitted releases.

As well as investing £34 million to protect the harbour’s water quality, we’re updating residents through our Beachbuoy app, as a trial, and taking reports of debris seriously via our beach patrols.

The surrounding bathing waters remain ‘excellent’ despite our permitted stormwater releases – evidence that our ongoing work is helping to protect the quality of Langstone Harbour’s water today and for the future.

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