A shocking report from a community group in Devon has found evidence of illegal dry spills in 14 different areas of the River Dart between 2021 and 2023.

According to Friends of the Dart, the worst spill occurred in Rattery, South Brent, where a total of 15 hours of sewage was found to have been released into the river.

Dry spills happen when untreated or partially treated sewage is discharged into watercourses during dry weather.

Save for some exceptions, it is an illegal practice as water companies are generally only permitted to use storm overflows when sewers become inundated during heavy rain.

The group said it considered a ‘dry period’ as four consecutive days with no rain, citing methodology used by the BBC.

Friends of the Dart said the release of sewage in Rattery was “alarming” because it suggested that the local system “is not fit for purpose”.

It said: “Despite assurances of infrastructure improvements, sewage spills appear to be worsening, which is especially worrying given the absence of rainfall to explain them.

“Dry spills are particularly concerning because they indicate a direct release of sewage without the mitigating effect of rainwater dilution, leading to higher concentrations of pollutants like bacteria, chemicals, and nutrients in rivers.

“This can have serious consequences for water quality, aquatic life, and public health, as these discharges can make rivers unsafe for wildlife and humans.”

The group said that although the analysis covered a three-year period, it was “impossible” to know how many more spills occurred in the Rattery in 2021 as there was no sensor (or Event Duration Monitor – EDM) in place at the time.

Although South West Water (SWW) has repeatedly blamed an increase in rainfall in 2023 (up by 34 per cent compared to 2022) for triggering a rise in the use of storm overflows, Friends of the Dart said the firm had failed to provide a response about the dry spill incidents.

SWW declined to comment on the specifics of the report to this paper but added: “We are clear that storm overflows must only be used when absolutely necessary and regard all unpermitted dry spills as unacceptable.

“There is no methodology to define a dry day spill. When numbers like these are reported in the media, an approved methodology is vital on this important subject. The EA also acknowledge that drain down times for catchments will differ and the methodology will include modelling data to assess spills more accurately. We continue to work with the regulator on this.

“Reporting standards of EDM data varies across the sector. It is important to note that SWW uses more stringent criteria for reporting storm overflow activity. We report all overflow activity over a one-minute duration, while some companies use a 15-minute duration methodology. This means we capture and report a greater number of spills.”