Sewage in our seas: how the decisions of the past still affect us today

Monday’s assembly reading came with a metaphorical and literal health warning, because it was all about sewage.

You will be aware of the shocking stories in recent years about how much raw sewage gets pumped into rivers and seas across the UK.

In 2021, this happened over 370,000 times; in 2022 this fell slightly to 301,000 due to drier weather; and last year it happened 399,000 times, an average of 1,090 per day. It seems almost unbelievable that in a developed country such as ours, this happens at all, let alone so much, and even more shocking is the fact that it’s been happening for decades without the public being made aware until recent times.

The reason it happens goes back around 170 years to the 1850s. This was the time of the Industrial Revolution when the population increased rapidly and millions of people started living in overcrowded cities. This led to a proliferation of diseases such as cholera and typhus caused by sewage getting into the water supply. The pollution got so bad in London, that parliament was cancelled in 1858 due to the stench that was coming from the Thames. Although this was happening before it was known that germs existed and were the cause of such diseases, it was clear that the problem of sewage in the water supply had to be addressed.

Two men were instrumental in proposing solutions, and the fact that the view of one triumphed over the other is why we have such a problem with sewage being dumped into our waters today.

Their names were Edwin Chadwick and Joseph Bazalgette, each committed to the building of a vast network of sewers that would solve this problem that was threatening to overwhelm British cities. Chadwick proposed that two sets of pipes be laid – one to carry sewage from toilets, the other to gather rainwater from roads and roofs. Unfortunately, the Commission set up to deal with this problem felt this was too complex and expensive, and Chadwick’s idea was rejected. Instead, the commission approved the idea of a civil engineer called Joseph Bazalgette to build a similarly vast network of sewers but one in which everything would be carried in one pipe. Bazalgette’s sewers were built and he was hailed as a hero who had solved many of London’s public health problems, so much so that his designs were used across Britain and indeed much of the developed world when it came to building sewers. No one asked questions about what happened to all the sewage because the cities were so much cleaner and outbreaks of water-borne diseases so much rarer.

The sewers built in London during the 1860s are still there, and they’re still used, as is the case elsewhere. Most sewage is of course treated and made safe, but when it rains heavily and the sewers fill up, the only way to prevent waste from our houses from coming back up through our sinks and toilets is to have an overflow system that dumps it in rivers or the sea. The more rainfall we have, the more this happens – largely because of a decision made in London back in the 1850s.

This problem is an example of what economists call ‘path dependency’ – when our current actions are constrained by historic decisions.

To solve it emphatically would mean digging up most of the pipes that go to most houses in the UK, which is neither practical nor affordable, with estimates suggesting it would cost around £600 billion. There is, at least, a plan worth up to £10 billion that will include installing the equivalent of thousands of Olympic-sized swimming pools to hold surges in rainwater that would otherwise overload the system, and treating more overflow spills so they have less impact on the environment when they enter our rivers and seas.

Unfortunately, it will be ordinary customers who will pay for these improvements in the form of increased water bills. I would also put this on the list of problems that are likely to remain when the school children of today reach the world of work, and one I hope their generation will prove better at solving than mine has been so far. In the meantime, if you’re at the beach in the UK at any point over the summer holidays, my advice would be to check the water quality before you go for a swim.