Victorian Sewage: Yesterday’s Solutions Can’t Keep Up With Today’s Problems

Out of sight, out of mind

Clean water and a way to eliminate waste. These are crucial to our survival and modern standard of living. Yet we don’t think much about it. That is because the infrastructure behind it
is often out of sight, out of mind, at least unless there is a problem.

And we get it, it isn’t flashy to think about running water and what goes down the toilet. But we’d like to invite you to do that for just a moment. Because the fact is that our modern sewage system, well it isn’t all that modern.

The outline of the problem

The basic structure of our modern sewage system comes from the Victorians. Specifically, it comes from a man named Sir Joseph Bazalgette. Before Bazalgette’s day, London’s sewage flowed directly into the Thames River. This was also the city’s drinking water, so you don’t need to be an expert to see the problem. The pollution caused numerous health outbreaks, so Sir Bazalgette developed a state-of-the-art sewage system. Well, state-of-the-art as of 1865.

If a system that old concerns you, we should point out that you only need to worry about it when it rains, and that never happens in the UK, right?

But let’s back up a moment. When the system was designed and when construction began, it was intended to handle the waste of about 2.5 million people. When it was completed it handled 4 million people. Today that number has doubled.

What this means is that the base flow, how it operates under normal conditions, is already elevated. Add to that a lot more rainwater than was ever expected, courtesy of all of our paved, non-porous surfaces, and you have a recipe for a Combined Sewer Overflow or CSO. Essentially, a CSO is exactly what it sounds like. Think of a sink that is draining at the same rate as water is coming in. Then crank up the faucet. That is increased base flow. Then dump a bucket of water in. That is a heavy rain event. And for our outdated sewer system, the result is sewage flowing back into the environment.


So what are those solutions? Developing more green space and storm gardens, natural ground that can soak up that excessive rainwater. Another solution is already being proposed. The Tideway Tunnel is a proposed “super-sewer.” It would intersect our existing system at locations that frequently cause CSOs and it would be the biggest leap forward in our sewer system since, well since Bazalgette.

Ultimately, the CSO problem was slow to develop and so a solution isn’t going to happen overnight. But if we start to think about it now, and start to plan for our growing needs, maybe that solution will be here sooner than we think. And our game-changing monitors can be there, in the pipes and in the streams, in the rivers and in the estuaries, to provide the real-time data that we need for those solutions.


18th January 2023
Tom McNamara


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