Nutrient Neutrality: Protect Our Rivers, Upgrade Systems & Unlock Developments

If you own a property with a septic tank in one of the four Somerset nutrient neutrality catchments, you may qualify for a free upgrade under WCI’s scheme. We install a modern sewage treatment plant at no extra cost to you. The phosphate reduction achieved generates betterment credits that we use in our credit scheme for developers. There is no charge to the homeowner, and the installation is handled by our own WCI engineers. For more information, please see the Free Upgrade Scheme page.

We hold credits in stock across all four Somerset catchments. For straightforward applications, credits can be supplied within days of enquiry. In one recent case, Taunton Schools, we provided a full NNAMS assessment and credits within five days after the original mitigation scheme fell through. If your application is time-sensitive, call us today.

A NNAMS is an assessment report that calculates your development’s phosphate load and advises on how to achieve neutrality. Most planning authorities in affected Somerset catchments require one as part of the nutrient neutrality condition. Our consulting engineers produce NNAMS reports and can coordinate credit supply so you are not managing two separate workstreams.

There are four catchments, including the River Tone, River Parrett, River Brue, and River Axe. Each covers a defined geographic area. The Parrett catchment is the largest, covering much of central and south Somerset (including the former South Somerset and Sedgemoor districts). The Tone covers the Taunton area and Wellington. The Brue runs through the Mendip Hills area. The River Axe extends into East Devon and Dorset. We hold phosphate credits in all four. 

Yes – Somerset Council updated its policy in December 2025, stating that developments no longer need to secure credits before submitting a planning application. However, credits are still required to discharge the nutrient neutrality condition before construction can start. If your site is in an affected catchment, you must buy credits during the planning process.

Phosphate credits represent a reduction in phosphate reaching a river catchment, typically achieved by upgrading old septic tanks to modern sewage treatment plants. When a developer buys credits, they are offsetting the phosphate loading their development will generate against a verified reduction made elsewhere in the same catchment. Somerset Council administers the credit system, and all credits purchased must come from an approved supplier. WCI is council-listed in all four Somerset catchments and provides credits where needed.