BBC uncovers 6,000 possible illegal sewage spills in one year

Regarding the BBC’s methodology, some of the water companies argue it did not take into account that some outlets have large catchment areas and it can take a few days for any rainfall to drain through their systems, i.e. sewage detected on a dry day may be the remnants from an earlier rainy day.

However, the BBC accounted for drain-down time by only considering a discharge a potential dry spill when there had been four consecutive days in the surrounding area without rain.

Helen Wakeham from the EA says the BBC’s methodology is, in fact, “more generous” to the companies than the EA’s.

Commenting on the results of the BBC’s investigation in general she said: “I’m not surprised, these networks haven’t been invested in for decades. That investment needs to take place.”

In May the UK’s top engineers and medical professionals warned in a public report the risk from human faecal matter in our rivers will increase without changes to the network and how we build our cities.

Dr David Butler, professor of water engineering at the University of Exeter, and co-author of the report, said investment from water companies has “not really been up to scratch”.

But he added that we must also rethink how we design our towns and cities.

“What we would like to see is reversing urban creep – that is well beyond the powers of a water company. You see it all the time, people concreting over their front garden,” Prof Butler explained.

“If you could unpick that it would help because that would reduce stormwater runoff and that would give us more capacity in our pipes.”

Reducing dry spilling would also help prevent excessive nutrients entering rivers from sewage discharging. The issue, which is also associated with agriculture, can cause excessive amounts of algae to grow, resulting in waterways becoming depleted of oxygen, killing off other animals like fish.

“[It] also can have knock-on health effects, because this algae can produce other toxic products which might be harmful to human health,” said Prof Evans of University of Leeds.