Penzance and St Erth Sewage Treatment Works Upgrades
Penzance and St Erth, Cornwall · Ongoing (Part of South West Water's long-term investment in environmental improvements and phosphorus removal); 2018 (equipment failure at St Erth STW) [St Erth Parish Council] · Part of South West Water's broader investment in environmental improvements and phosphorus removal across the region (e.g., £3.2bn five-year plan) [South West Water]
The judgement call
Account-gated at launchPenzance's sewage is transported to St Erth for treatment [Facebook (Mutual Aid Penzance)] - South West Water is undertaking a comprehensive phosphorus removal scheme across its STWs to protect river ecosystems [South West Water] - An equipment failure at St Erth STW in 2018 highlighted the importance of critical asset reliability [St Erth Parish Council]
Key engineering challenges
Ensuring effective treatment of wastewater for a significant population, including tourist fluctuations in Penzance [Implied] - Meeting environmental standards for discharge, particularly phosphorus removal [South West Water] - Maintaining and upgrading aging infrastructure to prevent failures and ensure resilience [St Erth Parish Council]
Project facts
- Client / owner
- South West Water
- Lead contractor
- —
- Lead designers
- —
- Project type
- upgrade
- Scale
- St Erth STW treats wastewater from Penzance [Facebook (Mutual Aid Penzance)]
- Disciplines
- Process; environmental; civil
- Standards & frameworks
- Environmental Agency regulations; Water Industry National Environment Programme (WINEP) (implied by phosphorus removal)
Sources: Facebook (Mutual Aid Penzance): https://www.facebook.com/groups/MutualAidPenzance/posts/1518412729087089/ (Accessed: 2026-06-10) - St Erth Parish Council: https://sterth-pc.gov.uk/2018/01/19/failure-at-sww-sewage-treatment-works-at-st-erth/ (Accessed: 2026-06-10) - South West Water (Phosphorus removal project): https://www.southwestwater.co.uk/about-us/what-we-do/engineering-projects/wastewater/phosphorus-removal-project (Accessed: 2026-06-10) - South West Water (Investment plan): https://www.southwestwater.co.uk/about-us/latest-news/one-year-on-how-south-west-waters-3.2bn-investment-is-starting-to-deliver-real-change (Accessed: 2026-06-10)