How is water monitored on The Isles of Scilly?

A coastal landscape with a large body of water, rocky shoreline at the edge of Peninnis headland under a clear blue sky.

Or perhaps the better question would be ‘is water quality monitoring making a difference on scilly’?

There are different types of water quality monitoring that happen on the Isles of Scilly, and everywhere else too. On the mainland, designated bathing waters are tested between May and September. DEFRA noted fourteen, and South West Water noted thirteen beaches that may have the potential to become designated bathing waters on Scilly, yet there are still none on the islands. This means there is no legal requirement for the testing of bathing water. However, bathing water quality testing has been observed on the Isles of Scilly and we want this evidence to be made public under the interests of public health - without it, how will South West Water support claims that water quality will not change? We also intend to work at getting our beaches designated for bathing in future to keep our swimmers and our wildlife safe. If you haven’t seen it yet, Channel 4’s Dirty Business is an eye-opening watch.

Drinking water monitoring is presently conducted on the Isles of Scilly by South West Water, and the Drinking Water Inspectorate reports on the little information held. Earlier data, if it exists, does not feature in official reports due to the late application of water legislation to Scilly. Following an Environmental Information Request to the DWI, there was a refusal to publish or provide a copy of the 2025 audit of the Isles of Scilly. They stated that, in the consideration of public interest, they would not provide this as it would interfere with their ongoing investigation and potentially prevent prosecution of the water provider.

An OFWAT investigation into South West Water’s operations on the Isles of Scilly found significant failings that they were unable to address due to the Local Enforcement Position granted to the company by the Environment Agency until post-investment operation, originally until 2025 but extended by the EA until 30th September 2027.

We are calling for:

  • Real-time, strict monitoring on all points of sewage discharge across the Isles of Scilly - not self-monitoring

  • Transparent monitoring and reporting of drinking water

  • Urgent compliance with all UK water legislation

  • Eventual designation and regulated monitoring of bathing waters

  • Behaviour-changing enforcement action - not fines - taken by regulatory bodies when failings are found