NutrientMonkey
Nutrient Neutrality Calculator
Start here. The protected site the scheme drains to and the nutrient it is assessed for — every default below follows from this choice.
For the report header only — none of it changes the budget.
Water in. What the new dwellings will discharge — from occupancy, water use and the treatment works' permit.
The land today. Only the areas of land whose use is being altered by the development. Export coefficients are indicative defaults — replace with the official catchment value for your soil / rainfall / NVZ.
The same land afterwards. The land cover present on that area once built (e.g. residential urban land, open urban land, greenspace).
Water out. Nutrient taken back out of the post-development surface-water load by drainage features. Leave at 0 if there are none.
The answer. (waste water − current land use + future land use − SuDS) × 1.2 precautionary buffer.
Free to use on screen. See an example report
Nutrient neutrality means a new residential development will not cause a net increase in nutrient pollution to a protected habitats site. Natural England catchments are assessed for nitrogen, phosphorus, or both — e.g. Poole Harbour and the Solent (incl. Chichester Harbour) are nitrogen; the River Avon (which discharges into Christchurch Harbour) is phosphorus; Stodmarsh and The Broads are both. Where a catchment requires both nutrients this tool calculates both budgets at once; they remain two independent budgets, each mitigated with its own credits. The nutrient budget is (waste water − current land use + (future land use − SuDS)) × 1.2, where the ×1.2 is Natural England's 20% precautionary buffer. Waste-water load = occupancy × units × water use (l/p/d, incl. NE's +10 l/p/d allowance) × 365 × nutrient concentration (mg/l) ÷ 1,000,000. For mains drainage the concentration is the waste water treatment works permit (with a separate post-2030 figure where a WINEP upgrade applies); for off-mains, NE's default total-nitrogen concentrations are 96.3 mg/l (septic tank) and 72.9 mg/l (package treatment plant), and total-phosphorus 11.6 mg/l (septic tank) and 9.7 mg/l (package treatment plant). One credit mitigates 1 kg of the nutrient per year. The land-use export coefficients vary by catchment, soil drainage type, rainfall band and NVZ status — this tool exposes them as editable fields so you can enter the value from the official Natural England calculator's lookup for your site. Where your LPA or Natural England require the statutory calculation, reproduce these figures in the current official NE catchment calculator. This tool is for guidance and planning support and is not a substitute for that calculator or for ecological/engineering advice.
A fully-branded, planning-ready PDF: catchment, waste-water load, current & future land use, SuDS, the pre- and post-2030 nutrient budget(s), the credits required and full methodology notes. Dual-nutrient catchments include both the nitrogen and phosphorus assessment.
£79 + VAT (20%)
Secure payment via Stripe · £79 + VAT (20%) = £94.80 total. Included: a planning-ready PDF with a unique Report ID (verifiable at energycount.co.uk/verify), re-download free for 24 hours and free re-export for genuine corrections within 1 hour (up to 5). A VAT invoice is emailed automatically — add your company name and VAT number at checkout. By paying you agree to our Conditions of Sale — the report is supplied immediately, so the 14-day cancellation right is waived on delivery.