Revamp Your Tank

Wiltshire Council is teaming up with Wessex Rivers Trust to improve water quality in the Hampshire Avon catchment. 

Fully funded grants are available to homeowners to upgrade their household septic tanks and help fight pollution in our precious chalk streams. More efficient non-mains sewage treatment reduces the level of nutrients from our waste water, and negative impacts on aquatic ecosystems and our drinking water.



- The property must be within the Hampshire Avon catchment and in Wiltshire.
- Must be close to a watercourse, connected to the Avon or one of its tributaries
- The applicant must be the homeowner or have the homeowner's permission.



To register your interest in the scheme, fill out the Expression of Interest Form. It is important that you identify accurately where your property is located, for Wiltshire Council to determine if you are eligible for the grant. Your form will be assessed and if you are accepted into the scheme you will be contacted about the next steps. Wiltshire Council will endeavour to inform you of the outcome within 6 weeks.


Further Information 

You can find out more on the Wiltshire Council Website or have a read of the FAQ's. We will also be hosting a number of live events so you can find out more about the upgrade initiative and ask us questions in person, follow us on social media to find out when and where these will be taking place.

Why Upgrade? 

Septic tanks are simply designed to separate out our liquid and solid waste using gravity. The solid matter is partially digested by bacteria, whilst the untreated wastewater soaks into a drainage field in the surrounding soil. These systems can release nutrient-rich wastewater which can eventually reach the rivers, contributing to river pollution.

Nutrient-rich wastewater increases blooms of algal growth - a process called eutrophication. Algae form green carpets across the water’s surface, blocking light and killing aquatic plants below the surface. With fewer aquatic plants, there are fewer essential microhabitats for small fish and insects and the whole river and its ecosystem suffers. In some of the more rural parts of our catchments, septic tanks are a notable source of nutrient enrichment in our rivers and surrounding landscape.

Upgrading your septic tank now could also save you difficulties when it comes to selling your property due to an Environmental Agency law that came in as of 2023:
GOV.UK: Environment Agency - General binding rules: small sewage discharge to a surface water.

Diagram of a septic tank with drainage field © Hampshire & Isle of Wight Wildlife Trust.


Upgrade Initiative

Replacing septic tanks with more effective package treatment plants could significantly reduce nutrient enrichment of our precious chalk streams. Restoring healthy ecosystems, benefiting plants, insects, and our characteristic species such as salmon, water vole, otter and birds, all of which rely on a clean and healthy river. Some of our most iconic wildlife, including the Atlantic salmon, are at risk of further decline due to deterioration in water quality.

The upgraded systems work in a variety of ways, depending on which is recommended for the property, from simple biological treatment, to using bursts of aeration. Not only will they separate solids and liquids, but they also biologically treat the effluent so that it can be discharged safely straight into a water course. If space allows, tertiary treatment can be added which remove even more nutrients.

You can find out more on the Wiltshire Council Website or have a read of the FAQ's. 

Diagram of a small sewage treatment plant © Hampshire & Isle of Wight Wildlife Trust


You Can Make a Difference

Our unique chalk streams currently need all the help they can get. By ensuring your domestic wastewater is treated to the highest of standards, we can maximise the environmental benefits and minimise the pollution potential of the effluent.

Revamp your tank and actively contribute to improving water quality - supporting the health of the river, wildlife and your community.