The Environment Agency has published data of how many times a storm overflow discharged sewage in the sea last year.

The Enviorment Agency publishes annually its Event Duration Monitoring data for 2022. This includes data from all 10 water and sewerage companies (WaSCs) operating in England, with information on the frequency and duration of storm overflow spills.

Devices that monitor sewage spills are now installed in just over 99 per cent of storm overflows in Devon and Cornwall.

Event duration monitoring data were returned from 13,323 storm overflows nationally during 2022 – with the duration and frequency of sewage spills now monitored at 91 per cent of storm overflows across the country. This is up from 12,707 in 2021 (equating to 89 per cent coverage).

The government has instructed water companies to install monitors on all storm overflows by the end of this year.

While the data show a 19 per cent reduction in the number of sewage spills nationally - down from 372,533 in 2021 to 301,091 spills in 2022 - this is largely due to last year’s below average rainfall.

In Devon and Cornwall 1,333 of storm overflows have now been fitted with monitoring devices – up from 1,102 in 2021 and now covering just over 99 per cent of storm overflows in the area.

The national data shows that in 2022:

• The average number of monitored spills per storm overflow was 23, compared to 29 in 2021.

• Three per cent of storm overflows spilled more than 100 times, compared to 5 per cent in 2021; and  18 per cent of storm overflows did not spill at all, compared to 13 per cent in 2021.

The data also show that in 2022 in Devon and Cornwall:

• The average number of monitored spills per storm overflow was 28.5, compared to 38.9 in 2021

• The total number of monitored spill events was 37,649, compared to 42,484 in 2021

• Total duration (hours) of monitored spill events in 2022 was 290,271, compared to 351,785 in 2021

Monitoring devices on just over 15 per cent of storm overflows operated less than 90 per cent of the time in 2022, compared to 13 per cent in 2021.

Nearly seven per cent of storm overflows spilled more than 100 times, compared to 10.4 per cent in 2021; and  23.6 per cent of storm overflows did not spill at all, compared to 15.4 per cent in 2021.

Storm overflows are a safety valve designed to release excess storm water from the sewerage system into rivers or the sea during periods of rainfall and/or snowmelt to ensure they are not overwhelmed. Water companies should only do this under strictly permitted conditions. EDM devices provide essential information about storm overflow use, helping to hold water companies to account.

The Environment Agency shares public concerns around storm overflows and is calling for urgent improvements in storm overflow maintenance, management and investment by water companies.

Clarissa Newell, Devon and Cornwall Area Environment Manager, said: “While the data show a reduction in the number of sewage spills from South West Water in 2022, this is due to last year’s below average rainfall.

“We are disappointed to see South West Water had a relatively high proportion of monitoring devices that were out of action for some of 2022.  It is a permit condition to ensure a device is installed, maintained and provides storm discharge data – we are working with South West Water to ensure all monitoring devices are operational and reporting data correctly.

“Sewage pollution can be devastating to human health, local biodiversity and our environment. We need to see tangible progress from all water companies, including South West Water, on reducing spills and acting on monitoring data, and we will continue to hold them to account.”

Environment Agency Executive Director John Leyland said: “The decrease in spills in 2022 is largely down to dry weather, not water company action.

“We want to see quicker progress from water companies on reducing spills and acting on monitoring data.

"We expect them to be fully across the detail of their networks and to maintain and invest in them to the high standard that the public expect and the regulator demands."