Ernesettle Sewage Treatment Works Upgrade (Phosphorus Removal & Capacity Planning)
Ernesettle, Plymouth, Devon · Ongoing (Phosphorus removal as part of SWW's long-term programme); Capacity planning for future growth up to 2035 [Plymouth City Council, South West Water] · Part of South West Water's overall investment in phosphorus removal and network upgrades (e.g., £140m across 82 projects in Exeter's sewage system, similar regional investments) [Instagram (Exeter), South West Water]
The judgement call
Account-gated at launchSaltash sewage is currently transported to Ernesettle STW; a future plan considers Saltash having its own treatment plant to create capacity [Plymouth City Council] - Part of a broader South West Water programme to upgrade treatment processes for phosphorus removal across multiple STWs [South West Water]
Key engineering challenges
Removing phosphorus from wastewater to protect river ecosystems and improve water quality [South West Water] - Managing existing capacity while planning for future population growth, including potential for a dedicated Saltash treatment plant [Plymouth City Council] - Addressing odour concerns from the local community [Facebook (Fred Thomas MP)]
Project facts
- Client / owner
- South West Water
- Lead contractor
- —
- Lead designers
- —
- Project type
- upgrade | capacity planning
- Scale
- Treats sewage from Saltash and parts of Plymouth; Capacity for growth up to 2035 [Plymouth City Council]
- Disciplines
- Process; environmental; civil
- Standards & frameworks
- Environmental Agency regulations; Water Industry National Environment Programme (WINEP) (implied by phosphorus removal)
Sources: Plymouth City Council (Agenda item - Drainage and Wastewater management): https://democracy.plymouth.gov.uk/mgAi.aspx?ID=113474 (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) - Instagram (Fred Thomas MP): https://www.instagram.com/reel/DObXsaPD-Ap/ (Accessed: 2026-06-10)