Soakaway Regulations 2025 (UK) – Plain-English Overview
Key expectations for soakaways and drainage fields in 2025: evidence, siting, discharge routes, and what officers usually want to see.
Need a checklist? Ask DrainageGPT with your soil type, space, and planned flows for a simple submission pack outline.
Big picture
- Evidence-led design: percolation test results and sizing calculations
- Siting: sensible separation from buildings, boundaries, watercourses, and wells
- Right discharge: surface water vs foul kept separate; wastewater routes must be compliant
- Records: drawings, test data, commissioning, and service/emptying logs
Percolation testing
Test in the proposed field area and record conditions. Averaged infiltration values drive trench lengths and spacing. Without this, systems are often undersized (fail early) or oversized (costly).
Discharge routes (plain-English)
- To ground (drainage field): only where soil is suitable and sized correctly
- To watercourse: typically requires a consent route and quality/flow limits
- Surface water vs foul: do not combine unless an approved design states otherwise
What officers commonly expect to see
- Site plan with separation distances
- Percolation results and design calcs
- Method statement/installation notes
- Commissioning and maintenance approach