Seven in ten major sewage leaks last year were caused by leaky pipes or a lack of treatment works to cope with demand, data analysis by MailOnline can has reveal.
After Environment Agency data from last month that English water firms dumped raw sewage into waterways for 3.6million hours last year, water companies pointed the finger on 2023 being a particularly wet year.
But campaigners have slammed claims from water firms that wet weather was to blame.Charles Watson, founder of River Action UK, told MailOnline ' "the weather" is becoming an increasingly untenable excuse', adding that it was like 'blaming the rain for the fact that you are getting wet because you failed to fix that hole in your roof'.
Analysis of EA data by MailOnline shows nearly 1.2million hours of raw sewage spills were caused by a insufficient hydraulic capacity - too few sewage works and pipes, the most common cause by far.
This is 48 per cent of the2.46million hours of discharges at the nearly 3,500 sewage works across England where an investigation has determined a main cause. A probe is triggered when more than 60 individual sewage spills are reported in one year.
OXFORDSHIRE: This sewage plant in Didcot, Oxfordshire spilled for 1,275 hours straight due to cracks and holes in pipes
LONDON: Discharge is seen flowing into the River Thames at Crossness sewage treatment works on March 27
'Blaming the rain because you failed to fix that hole in your roof': River Action founder Charles Watson
The Environment Agency says hydraulic capacity being the main cause of overflows 'indicates there is insufficient capacity (conveyance or storage) in the sewer network to cope with the wastewater flow plus typical rainfall entering the sewer network'.
More than 525,000 hours of sewage leaks last year were caused by infiltration - the sewers getting overloaded due to water leaking in through cracked and leaky pipes, forcing a storm overflow, around 21 per cent of major leaks.
'Confirmed exceptional weather' was the cause of 511,000 hours of raw sewage leaks - nearly 21 per cent - putting a dent in claims made by Water UK that wet weather was the cause.
Other maintenance issues, such as power failure, were the main cause of167,000 (7%) hours of major sewage leaks and 77,000 (3%) hours were caused by flooding.
Raw sewage discharges are meant to be released from storm overflows only in exceptional circ*mstances due to extreme weather such as torrential rain.
READ MORE:Thames Water sewage leak in picture postcard village lasted for 53 DAYS before finally stopping...and then starting again hours later: Locals say decade-long crisis has 'killed everything in the river'
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Last year was the sixth wettest on record, with1045mm of rain, compared to 788mm of rain in 2022. But both the frequency and duration of spills were also up on 2020 levels, which saw comparable amounts of rainfall.
Water firms blamed high rainfall for the high leakages, but this analysis shows that less than a quarter of major spills can be attributed to exceptionally wet weather. Both the frequency and duration of spills were also up on 2020 levels, which saw comparable amounts of rainfall.
River Action UK founder Charles Watson told MailOnline:'When digging into the detail of the EA data, it becomes increasingly apparent that blaming last year's atrocious levels of sewage spills on "the weather" is becoming an increasingly untenable excuse.
'One major stated cause of these huge levels of discharges is listed as "infiltration", or to put it more simply – the fact that sewage pipes leaked.
'While this phenomenon is clearly exacerbated by high rainfall causing ground water penetration into the system, the prime cause of the problem is the fact that these pipes have negligently been failed to be properly maintained over recent years.
'For the water industry to blame the weather is the equivalent of blaming the rain for the fact that you are getting wet because you failed to fix that hole in your roof.
'Instead of distributing £72billion of cash to shareholders as dividends, our water industry should have been using its now long spent financial resources to invest responsibly in maintaining its basic infrastructure.'
Muck covering the waters at Mill Brook inSouth Moreton, Oxfordshire where Thames Water dumped raw sewage for 1,275 hours straight earlier this month
Thames Water leaked raw sewage into a river in the idyllic Cotswolds village of Bledington for 338 hours straight (the water treatment station pictured)
The Bledington sewage treatment station which spewed raw sewage into Bledington Brook
Under-fire Thames Water saw zero hours of spills where the confirmed cause was high rainfall, with 76,000 hours of spills (50% of major ones), being caused by capacity, 42,000 hours (28%) being caused by leaky pipes and 35,000 (23%) being caused by other maintenance issues.
READ MORE: Idyllic Cotswolds village where shamed Thames Water has been leaking sewage into its river for 338 HOURS straight and counting - as families fear putrid water is poisoning their dogs, killing bees and harming farmers' crops
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This comes despite Thames Water previously blaming 'higher than average long-term rainfall across London and the Thames Valley, with groundwater levels exceptionally high for the time of the year' on sewage leaks.
Thames Water's parent company, Kemble, recently defaulted on its debts and shareholders have refused to provide new funding for investment, and instead want to jack up bills by 40 per cent.
The water company claimed that overflows caused by sewage capacity were 'heavily influenced by excessive rainfall', but the Environment Agency says these sites experienced 'typical rainfall' last year.
A Thames Water spokesperson said: 'We regard any untreated discharges as unacceptable, and we're committed to stopping them from being necessary. Where sewage capacity is listed as the primary cause in the Environment Agency data, this is heavily influenced by excessive rainfall.
'In 2023 we experienced above average rainfall, so our storm overflow system has operated to protect customers' homes during the wet weather. The overflows are designed to operate automatically when the sewer network is about to be overwhelmed by heavy rainfall, by releasing diluted wastewater into rivers, rather than letting it back up into people's homes.
'We have published plans to upgrade over 250 of our sewage treatment works. In many cases, this will improve performance and reduce the number of overflows during heavy periods of rainfall.'
United Utilities saw 320,000 hours of leaks caused by sewage capacity, 93,000 caused by other maintenance issues, 63,000 caused by infiltration and just 47,000 caused by exceptionally poor weather.
The water firm claimed that overflows due to 'hydraulic capacity' were due to 'constant high rainfall' - but the Environment Agency says these are in areas with 'typical rainfall'.
A United Utilities spokesperson told MailOnline: 'United Utilities has the highest proportion of combined sewers in the country - 54% compared to an industry average of around 33%. These figures show that the main cause of storm overflow operation in 2023 was "hydraulic capacity" – which is due to constant high rainfall.
'This categorisation is the first stage of an in depth investigation which we are now carrying out to understand the root cause of high spilling sites and to allow us to prioritise and plan the necessary remedial work – which will involve a proposed £3billion programme of investment from 2025 to 2030.'
Nearly all of Yorkshire Water's major leaks were caused by hydraulic capacity, with 357,000 hours (84%) of raw sewage being discharged last year because of this. Just 24,000 hours (6%) of sewage leaks were caused by exceptional weather.
Total hours water companies in England leaked sewage into rivers, lakes and the sea in 2023 shown by the areas they cover
Exceptional weather was listed as the biggest cause of leaks by just two firms, Anglian Water - which saw 116,000 hours (74%) leaked because of rain - and Severn Trent Water, which saw 142,000 hours of leaks because of the weather.
A Water UK spokesperson said: 'We recognise the current level of spills is unacceptable and have a plan to sort it out. Water companies in England want to invest more than £10 billion to cut sewage spills by nearly 40% by 2030.
'Heavy rainfall and high groundwater play a significant role in increasing the number of spills and climate change is making extreme weather more common.
'This is why we need to radically increase the capacity of our network by building thousands of massive storm tanks to hold rainwater and invest in nature-based solutions to stop rainwater getting into sewers in the first place.
'We now need the regulator Ofwat to give us the green light so that we can get on with it.'
