Opens NutrientMonkey. Pick Solent from the catchment list and the nitrogen toggle locks to match.
Stuck behind a Solent nutrient condition?
The Solent was the catchment that started it all, and it’s still the busiest. It covers a huge swathe of Hampshire and reaches into West Sussex and the Isle of Wight — and crucially it includes Chichester and Portsmouth Harbours, which catch a lot of people out.
If your site drains to Solent (incl. Chichester & Portsmouth Harbours), the planning authority can't grant permission until you've shown the scheme is nutrient neutral — that it won't add nitrogen to a catchment that's already overloaded. NutrientMonkey gets you the number: build the assessment on screen, watch your budget in kg/year update as you go, and export the planning-ready report when it's right.
Which nutrient applies here
The Solent is nitrogen-led: nitrogen from new housing fuels green algal mats that damage the internationally protected harbours and their bird populations. That matters, because the methodology and the credits differ by nutrient — and neighbouring catchments often differ. NutrientMonkey flags the Solent catchment for nitrogen and locks the tool to match, so the assessment is right from the start.
How the Solent calculator works
- Pick Solent from the catchment list — it's pre-flagged for nitrogen.
- Enter the dwellings & waste water — occupancy, water use (125 or 110 l/p/d plus NE's allowance) and the drainage route (septic, package plant or mains permit).
- Add land use & SuDS — current vs future land cover and any sustainable drainage, with editable export coefficients for the Hampshire, West Sussex & Isle of Wight catchment values.
- Export when ready — a branded, planning-ready PDF with the budget in kg/year and every input documented.
Honest about what it is
This is a nutrient-methodology assessment built to support your Solent planning application — fast, clear and ready to discuss with your case officer. The official Natural England catchment calculator remains the statutory tool, and your figures should reproduce in it; the report states this plainly. Want it handled end to end? That's what we're here for.
Frequently asked questions
Which nutrient applies in the Solent (incl. Chichester & Portsmouth Harbours) catchment?
The Solent is nitrogen-led: nitrogen from new housing fuels green algal mats that damage the internationally protected harbours and their bird populations. A compliant scheme has to be neutral for nitrogen. NutrientMonkey locks the nutrient toggle to match the Solent catchment automatically, so you can't pick the wrong one.
Is the Solent calculator free to use?
Yes — selecting the catchment, entering your dwellings and watching the budget update in kg/year is completely free. You only pay £79 +VAT (£94.80 inc VAT) to export the planning-ready PDF report.
How is the Solent nutrient budget worked out?
It follows Natural England's published nutrient-budget methodology — waste water, current and future land use, SuDS, then the final budget with the ×1.2 (20%) precautionary buffer. For new homes the waste-water term does most of the work and is computed exactly.
Is this the official Natural England calculator?
No — it's a fast, planning-support assessment that implements NE's methodology, and the report says so. The official NE catchment calculator remains the statutory tool, and your figures should reproduce in it.
In a different catchment?
NutrientMonkey covers every Natural England catchment.
Or jump to another part of the country:
- Poole Harbour N
- Tees (Teesmouth) N
- Lindisfarne N
- Stodmarsh N & P
- The Broads N & P
- River Wensum N & P
- Chesil & the Fleet N & P
- Hornsea Mere N & P
- Oak Mere N & P
- Rostherne Mere N & P
- West Midlands Mosses N & P
- River Clun N & P
- River Avon (Christchurch) P
- Somerset Levels & Moors P
- River Itchen P
- River Axe P
- River Camel P
- Derwent & Bassenthwaite P
- River Eden P
- River Kent P
- River Lambourn P
- River Lugg P
- River Mease P
- Esthwaite Water P
- Peak District Dales P
- Roman Walls Loughs P
Or go back to the main NutrientMonkey calculator.
Wider planning support
Nutrient neutrality is rarely the only condition on a scheme. Our energy statements service and the wider SAP & compliance team cover the rest of the planning and Building Control picture — get a quote and we'll talk it through.