A petition demanding the highest standard of sewage treatment for the Isles of Scilly closed its initial phase on 8 September 2026 with 2,238 signatories and was submitted to the Council of the Isles of Scilly Scrutiny Committee on that date, according to a campaign page hosted on the 38 Degrees platform and published on 9 September 2026 (Home - 38 Degrees). The campaign, run by Environment Action Scilly, argues that South West Water has only committed to secondary treatment and that adding UV disinfection would improve safety and reduce environmental impact.
The petition also lists the campaign's headline asks: secondary sewage treatment and UV disinfection on all inhabited islands, effective regulation and accurate monitoring, preservation of the islands' highly protected marine environment, and well-maintained water infrastructure and equipment, as set out on the petition page published 9 September 2026 (Home - 38 Degrees).
What happened
Environment Action Scilly started the petition under the title "Give Scilly the Highest Standard of Sewage Treatment" and the page tracks signature milestones, including 650 signatures and 1,500 signatories, the latter figure described on the page as "almost the population of St Mary's," according to the 38 Degrees petition page published 9 September 2026 (Home - 38 Degrees).
The campaign states that the petition was scheduled to be submitted to the Council of the Isles of Scilly Scrutiny Committee meeting on 8 September 2026 and that, once submitted, it would be filed alongside the listed organisations and representatives, with 2,238 signatories recorded, per the 38 Degrees page published 9 September 2026 (Home - 38 Degrees). The page adds that the petition site "will remain open so we can keep you updated with proposals and responses" and asks supporters to "share our petition far and wide in one last push," as written on the 38 Degrees page published 9 September 2026 (Home - 38 Degrees).
Alongside the petition, a separate local effort is underway: the page reports that "a group of local residents are hoping to apply for bathing water status for Porthmellon, Porthcressa and Old Town Bay on St Mary's," with responses to be shared with DEFRA subject to landowner permission from the Duchy of Cornwall and Council of the Isles of Scilly, per the 38 Degrees page published 9 September 2026 (Home - 38 Degrees). The page frames the wider ask in a direct line: "Because in 2026 there are no excuses for sewage pollution," as written on the 38 Degrees page published 9 September 2026 (Home - 38 Degrees).
Specification read
The 38 Degrees page does not report any flow rate, BOD, COD, population equivalent or installed-capacity figure for the Isles of Scilly's sewage works, so a precise design figure cannot be quoted from the sources. The combined population of the inhabited islands is small in absolute terms: the petition itself notes that 1,500 signatories is "almost the population of St Mary's," implying an island population of roughly 1,500 (general industry range, not from the sources), per the 38 Degrees page published 9 September 2026 (Home - 38 Degrees). For a community-scale works in this bracket, the typical treatment train runs screening to primary clarification to a biological stage (commonly MBBR or SBR for small, variable flows) followed by tertiary filtration and disinfection, with UV commonly used where bathing-water, shellfish-water or sensitive marine discharge consents apply (general industry range, not from the sources).
This story bears directly on the secondary-to-disinfection step of that train. The campaign's specific engineering ask is the addition of UV downstream of whatever secondary stage South West Water installs, on the basis that "UV Disinfection substantially increases the safety of water for people, and reduces the environmental impact," as stated on the 38 Degrees page published 9 September 2026 (Home - 38 Degrees). For a buyer or operator with a small-island or coastal works discharging to a designated or proposed bathing-water site, with secondary biological effluent and a UV-ready flow path, the procurement focus here is the disinfection stage and the monitoring/regulator evidence pack around it. Specifiers working on a comparable package can start from our Integrated Sewage Treatment overview and our Disinfection Equipment overview, and benchmark the broader small-community train against our Municipal reference set.
FAQ
What is the campaign actually asking South West Water to do?
The petition asks for secondary treatment plus UV disinfection on all inhabited islands, along with effective regulation, accurate monitoring and well-maintained infrastructure, per the 38 Degrees page published 9 September 2026 (Home - 38 Degrees). At this stage it is a campaign ask submitted to the Council of the Isles of Scilly Scrutiny Committee, not a confirmed scope change.
What has South West Water actually committed to?
According to the campaign, South West Water has "only committed to secondary treatment," with no UV step confirmed, per the 38 Degrees page published 9 September 2026 (Home - 38 Degrees). A buyer scoping this should treat UV as a campaign ask, not a contracted item, until the utility or the council confirms otherwise.
What is the indicative cost and lead time for adding UV to a small community works?
The 38 Degrees page does not report a cost or lead time for the UV upgrade. Indicative budgets and lead times vary widely with flow, effluent quality, lamp type and civil works, but a small-community UV package typically sits at the lower end of capital cost and short-lead category within a disinfection retrofit (general industry range, not from the sources).
What happens next on the bathing-water side?
The page reports that residents are preparing a bathing-water application for Porthmellon, Porthcressa and Old Town Bay on St Mary's, and that responses will be shared with DEFRA if the Duchy of Cornwall and the Council of the Isles of Scilly give landowner permission, per the 38 Degrees page published 9 September 2026 (Home - 38 Degrees). A formal bathing-water designation would tighten the discharge consent and strengthen the case for UV in the disinfection stage.
