Nutrient Management in Planning and Development

In this section

New All Wales Calculator (10/12/25)

The All Wales Nutrient Budget Calculator is a free tool for assessing the likely nutrient impact of development proposals. It helps applicants:

  • Identify whether nutrient neutrality is required
  • Calculate total nutrient load in kg/yr
  • Plan appropriate mitigation based on site specifics

We recommend using this tool. Use the calculator if your development:

  • Lies within a SAC catchment
  • Increases discharge to a WwTW draining to a SAC
  • Increases overnight stays or visitors/workers from outside the catchment

Supporting resources:

Calculator Guidance

Frequently Asked Questions

Mitigation Guidelines (Teifi, Tywi, Cleddau)

Mitigation Measures

All mitigation must be:

  • Based on the best available evidence
  • Precautionary in nutrient reduction assumptions
  • Effective beyond reasonable scientific doubt
  • Legally secured in perpetuity (80–125 years)
  • Maintained and monitored over time
  • Implemented and fully operational before occupation
  • Enforceable by planning condition or agreement
  • Upgrades cannot be used as mitigation unless confirmed deliverable by Dŵr Cymru and NRW.

We require applicants to submit:

  1. Details of how the measure prevents adverse SAC effects
  2. Nutrient neutrality calculations
  3. Implementation plans and delivery roles
  4. Maintenance responsibilities
  5. Monitoring strategy

Private Treatment Plants and Discharges to Ground

Where development proposes the use of private sewage treatment systems that discharge to ground, NRW advises that a conclusion of no likely significant effects can only be reached where all of the following criteria are met:

  • Domestic wastewater only, discharged to ground (not surface water).
  • System built to BS 6297:2007 + A1:2008.
  • Maximum discharge less than 2 m³/day.
  • Drainage field more than 40 m from any surface water.
  • Drainage field more than 50 m from any SAC boundary or any other drainage field.

Applications must include sewer connection justification, system specifications, scaled layout plans, and percolation test results demonstrating compliance with BS 6297.

See  Advice for planning applications affecting nutrient sensitive Special Areas of Conservation for full requirements.

We remain committed to supporting developers and finding practical, fast, and fair ways to unlock sustainable development in affected catchments.