TWO wastewater treatment works are being upgraded in a bid to reduce the amount of raw sewage pumped into Hampshire rivers after heavy storms.
A Southern Water facility at West Wellow is being equipped with three new tanks, increasing the amount of wastewater it can treat and reducing the likelihood of effluent being discharged into the River Blackwater.
Wessex Water is about to embark on a similar project in the New Forest in a move that aims to protect the River Avon.
It follows widespread controversy about the amount of sewage being pumped into rivers and coastal waters using what are known as storm overflows.
Most of the UK has a combined sewerage system, which means both rainwater and wastewater are carried to sewage treatment works in the same pipes.
Water companies are allowed to use storm overflows only in exceptional circumstances, such as heavy rain, to prevent the system from being overloaded.
But new figures show sewage was released into England's waterways more than 300,000 times last year.
The £3m upgrade at West Wellow is part of a £2bn bid by Southern Water to improve its environmental performance across the region.
Project manager Taniko Aston-Kolek said: "We understand the concerns around storm overflows. One way we can reduce them is by significantly investing in our assets and increasing the amount of wastewater we can treat, especially when there is heavy rain."
Wessex Water is spending £1.8m on a seven-month project to boost the efficiency of its Ringwood works.
A new tank will increase the site's capacity by almost a third, allowing nearly 1.5 million litres of water to be retained before being treated and discharged into the Avon.
The work is part of Wessex Water's £3m-a-month investment in tackling issues surrounding the use of storm overflows.
More than £150m is being spent on nearly 100 projects aimed at reducing their use by a quarter.
Wessex Water project manager Kirstie Hearn said: "The Ringwood centre treats wastewater from the local population which is expected to grow in future years.
"By adding this extra storage we can make it more resilient during heavy storms, easing the pressure on the sewer system and reducing the occasions that overflows operate.
"The new tank will make sure we can store more of this combined rain and wastewater before treating it and returning it safely to the environment."