0 Live Updates arrow
Account Login

Improving how we treat wastewater in the New Forest

Southern Water is investing £30m to improve the functioning of key sites in the New Forest and reduce the environmental impact on the local area.


We’re increasing how much wastewater we treat in Brockenhurst, Lyndhurst, Sway and Pennington. At Sway and Brockenhurst, we are also reducing the levels of phosphorus and iron we release. This work will improve the quality of water released into the local environment. 

We have engaged with the community in Sway ahead of work starting at Sway treatment works in September 2023.

Sway Wastewater Treatment Works

What is the purpose of the scheme?

  • We are investing 6.5m in improvements at our site in Flexford Lane, Sway
  • We will increase how much wastewater we treat
  • We will also reduce the levels of phosphorus and iron we release

An image of a river in the countryside

What are the benefits of the scheme?

  • We will release an improved quality of water to the environment (River Avon) by reducing phosphorous and iron levels
  • We will treat more wastewater to prevent spills to storm tanks in dry weather and meet predicted future population growth

What equipment are we installing?

  • a settlement tank
  • A filtration system to improve final effluent quality
  • kiosks for dosing chemicals to help reduce the phosphorus levels
  • electrical panels and monitoring equipment
  • hydraulic upgrades so that we can treat the increased flows

Where will we install the equipment?

All equipment will be installed within the boundary of the site:

A map of where the equipment will be used in the New Forest

How will we minimise disruption to you?

  • start main construction activity in September
  • work during daytime hours only - 7.30am – 5.30pm Monday – Friday
  • Assess noise impacts from the new equipment to make sure they are within acceptable levels
  • Odour levels are likely to improve as we are increasing how much water we treat
  • manage deliveries and traffic to the site using a Traffic Management Plan
  • repair any defects to the access track
  • re-plant and landscape to minimise visual impact
  • Please note – ground investigations (trial holes) in July involving small plant machinery

How can you contact us?

Your questions answered

We’re investing 6.5m in improvements at our site in Flexford Lane, Sway. We’re increasing how much wastewater we treat, to a higher standard. We will also reduce the levels of phosphorus and iron we release to the environment.

We will release an improved quality of water to Avon Water by reducing phosphorous and iron levels. We will treat more wastewater to prevent spills to storm tanks in dry weather and meet predicted future population growth.

Southern Water has separate plans to monitor wastewater flows in the catchment to try and assess this issue.

No, the flow coming into the works stays the same, but we will treat more to a higher standard.

No. phosphorus and iron reduction is the priority for this scheme, as agreed with the Environment Agency.

We are building a new filtration system and settlement tank capacity at the works.

The new settlement tank will require ground excavation and installation of a preformed tank liner.

The filtration system will be installed on a new concrete platform at existing ground level.

Where possible, manufacture and fabrication will be completed off site to minimise site works and disruption.

We routinely remove sewage from the site. This will continue fortnightly.

The number of construction vehicles travelling to and from the site will vary during the construction work, but we will manage this to minimise the impact. 

At peak times of construction, we estimate that there will be approximately 10-15 site vehicles and lorries per day, in and out of the site, for a period of about 4 weeks. This will reduce to 5-10 movements per day, during the remainder of the construction period.

After construction, there will be deliveries of chemicals every two months to the site, which we use to treat the wastewater.

We have informed the wider operational team about the inconvenience caused to residents by leaving any lights on. We apologise for this and hope that this will help avoid this happening again.

We plan to work Monday – Friday, 7.30am to 5.30pm. We will start construction activities at 8am to minimise disruption in the morning. There is no intention to work on Sundays or Bank Holidays.

There will be noise when we do certain construction activities. We will limit such activities to daylight hours. We will conduct a site briefing to make sure that workers keep general noise to a minimum.

We are installing solid, wooden hoarding around the southern boundary to reduce noise, dust, and visual impact.

Yes, we are planning a replanting scheme which we will implement as soon as the planned work is complete.

Yes, there is a small amount to cut back. We could not do this previously due to nesting birds. There are no hedgerows to remove. There are small trees to remove when we return to site.

Our staff will park within the treatment works so that we leave you space on the access road.

We will instruct staff to avoid parking on the access road and will include this in the traffic management plan. We will also ask our suppliers to comply with this.  

We’ll have a temporary office, parking, and facilities for the workers on site, away from residential areas.

The site won’t change too much, as it will remain within the existing boundary and the new equipment that we’re building is of a similar height to existing structures.

Please contact Matthew Thompson, GTB Communication and Communities Lead on 07810 655423. Alternatively, call our 24hr contact centre on 0330 303 0368 and say you are ringing about Capital Projects, Project Reference Number (PRN) 752080.