Phosphate calculator 2024
The latest phosphate calculator is available below:
Somerset Phosphate Budget Calculator (March 2024)
The step-by-step guide video on how to use the calculator is available here:
Natural England have confirmed they support the use of our phosphate calculator. Their letter of support is available here:
23 October 2023
A document which summarises the key differences between the previous version and the updated calculator is available here:
March 2024
For reference, ‘V1’ refers to the March 2021 version of the Phosphate Budget Calculator, and V2 is referring to the February 2024 version of the Calculator.
Phosphorus sensitive catchment area
The Secretary of State for the Environment, Food and Rural Affairs has designated that Somerset Levels and Moors Ramsar Site as a ‘Phosphorus sensitive catchment area’. More information on this can be found here: Notice of designation of sensitive catchment areas 2024 – GOV.UK
The effect of this notice is that within these areas, water companies must guarantee that wastewater treatment works serving a population equivalent to more than 2,000 meet specified nutrient removal standards by 1 April 2030. As a decision making tool for the Local Planning Authority and developers, the February 2024 phosphate calculator allows you to calculate mitigation post 2030. In addition, as within the previous version of the calculator, the February 2024 phosphate calculator allows users to calculate ‘Post 2025’ improvements which will be put in place under Wessex Water’s AMP7.
Next steps
You should:
- Use the update calculator to find out the phosphate impact of your proposal.
- Submit this information to support your planning application. Please note that you can save the output from the calculator as a PDF file to support your application.
Planning applications submitted on or after Thursday 15 February 2024 will need to use the new calculator (February 2024 version).
If your planning application was submitted before the above date, you may wish to rerun the phosphate budget calculations if you have a planning application pending a decision, but this is not required.
Within the 3 affected river catchment areas which feed into the Somerset Levels & Moors Ramsar site, a planning application will only be able to proceed if:
- the proposed development is phosphate neutral
- you can identify and secure mitigation to make it nutrient neutral
Once you have used the calculator and have an understanding of how much mitigation a development will require, you will then be able to consider what your options are for mitigation. In order to help you move forward, some guidance has been produced which includes:
- Nutrient Neutrality in Somerset: Guidance for Applicants, available here: Phosphates – Guidance, Template Documents and Useful information
For small scale schemes that propose the upgrade of a poorly performing septic tank to a more phosphate-efficient Package Treatment Plant, Somerset Ecology Services together with Natural England, have prepared Interim Guidelines which provide details on how in certain circumstances, off-mains drainage systems may not trigger the tests for ‘significant effects’ to require a Habitats Regulations Assessment. The guidelines are available below:
October 2023
If you have any queries, please speak to your Case Officer. Alternatively you can email your query to phosphates@somerset.gov.uk.
Previous version
The previous version of the phosphate calculator is available here:
Phosphate Calculator V1 (March 2021)
Note: If you submitted a planning application before Thursday 15 February 2024 you may wish to rerun the phosphate budget calculations from this calculator if you have a planning application pending a decision.