The Great Sewage Scandal

OUR ANALYSIS

It’s long been known that the recycling of sewage is an economical option to solve the pressure on water resources. However, to avoid health risks to humans, bacteria in sewage must be removed, otherwise, consumption may result in risks to a bather's health.

Despite this, in England and Wales, raw (untreated) sewage is being dumped into waterways, resulting in traces of E. coli (EC) and Intestinal Enterococci (IE) being found in our bathing waters, resulting in the UK ranking 25th out of 30 European countries for bathing water quality.

With this in mind, we decided to conduct our very own data analysis of over 16,000 sites, alongside historical bathing water quality samples, and gridded precipitation observations collected from the Environment Agency and the Met Office respectively, to identify how bad the sewage pollution issue really is.

For more detail, read our methodology.

A COMPARISON OF BACTERIA IN BATHING WATER, 2017 - 2022

When comparing the annual averages of the 95th percentile of EC count in bathing waters between 2017 and 2019, and 2020 and 2022, there has been a 19.91% increase. In the same period, the average IE count also increased by 21.29%.

We looked at the increase in the concentration of EC and IE bacteria found in bathing waters within a 5km radius of overflow sites across England, comparing annual averages of the 95th percentile between 2020 and 2022 to the three-year period prior in 2017 and 2019, to identify how much the levels of bacteria have changed.

Scientists say that the presence of E. coli in water is a strong indicator of sewage waste contamination. Our research found the highest level of EC in bathing waters within 5km of spill sites was in 2020, where the 95th percentile of EC count (cfu/100ml of water) was 280.71.

From our analysis of the presence of IE bacteria in bathing waters between 2017 and 2022, 2022 recorded the highest 95th percentile of IE count (cfu/100ml of water). The average for the year was 192.44, which is 7.95 (cfu/100ml) higher than the year before (2021), and 20.36 (cfu/100ml) higher than in 2017.

BATHING WATER QUALITY BY LOCAL AUTHORITY

After analysing the average annual EC and IE counts between 2020 and 2022, we attributed a normalised bathing water quality score out of 100 to each local authority. The higher the score, the better the bathing water quality.

THE 10 LOCAL AUTHORITIES WITH THE HIGHEST BATHING WATER QUALITY SCORE BASED ON THE COUNT OF FAECAL INDICATOR ORGANISMS, 2020 - 2022

The local authority with the highest bathing water quality score is Rochford in the East of England, with a score of 95.45 out of 100. The area recorded an annual average EC count of 42.93 and an annual average IE count of 56.80 (cfu/100ml of water) between 2020 and 2022.

Following closely behind in second is the New Forest, situated in the South East of England. This local authority was awarded a bathing water quality score of 93.2 out of 100, thanks to the average annual EC count being 78.98 and the average annual IE count being 28.67 (cfu/100ml of water).

Third goes to Bournemouth, Christchurch and Poole, based in the South West of England. The popular coastal towns recorded an average annual EC count of 58.05 and an average annual IE count of 68.50 between 2020 and 2022 (cfu/100ml of water), resulting in a score of 91.7 out of 100.

THE 10 LOCAL AUTHORITIES WITH THE LOWEST BATHING WATER QUALITY SCORE BASED ON THE COUNT OF FAECAL INDICATOR ORGANISMS, 2020 - 2022

The local authority with the lowest bathing water quality score is North East Lincolnshire, with a score of 2.25 out of 100. The area recorded an average annual 95th percentile of EC count of 1,070.75 and an IE count of 745.95 (cfu/100ml of water) between 2020 and 2022—the highest average annual IE count of all local authorities we analysed.

Second goes to the popular seaside hotspot of Brighton and Hove, based in the South East of England, with a bathing water quality score of 6.05 out of 100. This score was awarded due to the local authority recording an average annual 95th percentile of EC count of 1,070.75 and an IE count of 745.95 (cfu/100ml of water) between 2020 and 2022.

Following closely behind in third is Sefton, based in the North West of England. The area recorded an average annual 95th percentile of EC count of 1,037.33 and 385.67 for IE between 2020 and 2022 (cfu/100ml of water), resulting in a score of 7.55 out of 100.

THE 10 LOCAL AUTHORITIES THAT HAVE SEEN THE GREATEST PERCENTAGE INCREASE IN FAECAL INDICATOR ORGANISMS, 2017 - 2022

We analysed the highest average annual 95th percentile of EC and IE counts (cfu/100ml of water) for each local authority in England between the years 2017 and 2019 and 2020 and 2022, to identify which areas had the largest increase in faecal indicator organisms (E. coli and Intestinal Enterococci). From this, we attributed each local authority a normalised score out of 100—the lower the score, the better.

The local authority with the highest deterioration rate was Brighton and Hove, resulting in a water quality degradation score of 98.5 out of 100 in the southeastern city. The annual 95th percentile of EC (cfu/100ml) increased by 671.2% in the last three years in comparison to the three-year period prior (2017 - 2022). IE also saw a significant increase of 895.92%.

The South Eastern local authority of Chichester follows, with the second-highest deterioration rate between 2017 and 2022. The city saw the annual 95th percentile of EC (cfu/100ml) increase by 568.76%, and IE by 498.18%, resulting in a bathing water quality degradation score of 97 out of 100.

Portsmouth and Havant, both also based in the South East, have been awarded a bathing water quality degradation score of 92.55 out of 100 for having one of the greatest percentage increases in EC and IE in the last three years in comparison to the three-year period prior (2017 - 2022).