BBC research indicates that upwards of 76,000 sewage discharges were logged subsequent to the deployment of fresh sensors at waste overflow locations across Scotland.
Scotland Sees New Sewage Discharges
Installing 1,009 sewer monitors throughout 2024 elevated the coverage of the Scottish Water network being monitored from 6% to 30%. These upgrades revealed tens of thousands of discharges that previously went unrecorded, affecting locations including Loch Lomond.
Glasgow’s River Clyde was one of the most heavily impacted waterways, receiving almost 6,150 spills last year, or the equivalent of 17 a day, based on Scottish Water figures. When adding in the Clyde Estuary, the Firth of Clyde, and other unnamed tributaries, that figure almost doubles to nearly 14,200 spills.
The Clyde Estuary also recorded the longest duration of spills at more than 25,000 hours.
The River Clyde followed with more than 15,000 hours of discharges. Among newly monitored sites, the Barceloy Mill Burn in Dumfries and Galloway received the most spills last year, with a total of almost 3,500.
Across the monitored network, data suggests that 225 sites recorded no spills and 525 recorded fewer than 10.
Regulators Explain Overflow Operations
Overflow sites act as relief valves designed to prevent sewer systems from becoming overwhelmed during heavy rainfall, stopping water from flooding homes, businesses, and streets. These permitted locations release untreated or partially treated waste into natural waterways during deluges.
The number of overflows with monitoring rose from 273 to 1,275 in 2024. Last year saw a count exceeding 100,000 spills accumulating nearly 277,000 hours, equating to a daily average of roughly 274.
Just under 12% of these overflows are legally required to report data to the regulator, the Scottish Environment Protection Agency. Sepa said it has a “risk-based approach,” which prioritises areas for monitoring based on population and environmental need.
None of the new monitors were required to be reported to Sepa. “The vast majority of those spills aren't harmful to the environment because they're nearly always about rainwater,” Simon Parsons, director for wastewater at Scottish Water, said, while noting that the expanded monitoring has enhanced comprehension of the sewer infrastructure.
Communities and Surfers Find Pollution
In West Lothian, the River Almond recorded 1,270 spills totalling nearly 1,500 hours last year. Local campaigner Ruth Plevin voiced concern over invisible pollutants affecting the waterway.
“It’s what’s not visible that is our concern – the microplastics, the pharmaceuticals, the agrichemicals, stuff that you can’t see,” said Ruth Plevin, member of the River Almond Action Group.
Further east at Belhaven in East Lothian, Brian Allen tests local water weekly for E.coli and intestinal enterococci by sending samples to an accredited laboratory.
Sepa typically monitors bathing water quality at approximately 80 Scottish sites between May and September. Allen told the BBC.
Plans Target Future Monitoring
Simon Parsons, of Scottish Water, said the monitors help identify problems in the system.
“We can actually identify those areas where we need to think about investment,” Simon Parsons, director for wastewater at Scottish Water, said.
While monitoring in Scotland remains far lower than in England, which has 100% coverage, Scottish Water said that its monitoring had now grown to about 50%. The utility is aiming to reach 100% over the next five to six years.
