This blog, written by Associate Martin Hurst, first appeared in Green Alliance in October 2023

The first toilets in the UK were on Orkney, dating to 3000BC. Though the Romans and Henry VIII had a go, the subsequent history of our sewage treatment isn’t a happy one. As recently as 1850 people were catching cholera from water contaminated with human waste.

Despite that, it took the great stink of 1858 for parliament to fund the first comprehensive sewer system for London. Even in the 1980s, untreated sewage was routinely pumped out to sea a couple of hundred meters from popular beaches. A major reason for the privatisation of water was to raise money to stop this. Now, although sewage treatment is somewhat better, many rivers and marine environments are still poor, and we still see discharges of untreated sewage.

Why do we still discharge untreated sewage into our rivers and seas? 

Around half the sewers in this country, taking wastewater from our homes to sewage treatment works, are ‘combined sewers’: built by the Victorians and Edwardians to take both sewage and rain water. They built them well: the sewers in London could still cope with all the capital’s sewage. But our towns and cities have changed. When people had front gardens, the roads were made of dirt and there were no car parks most of the rain would soak into the ground. Now it runs from concrete into the drains and then into the sewers.

When this happens, the amount of sewage, combined with rainwater, is too much for treatment works to cope with. Some is ‘stored’ – in storm tanks and the new Thames Tideway tunnel – but some must be discharged into rivers and seas through Combined Sewer Overflows (CSOs). The sewage is diluted, but that doesn’t stop it damaging the environment and it’s not great for wild swimming.

The Environment Agency issues permits for these discharges, so many are legal. However, water companies don’t have a great record of sticking to the terms of these permits or keeping the filters clean to stop the really yucky bits getting out. Although most of the bad press is around Thames and Southern Water, and most recently Wales, more of the overflows appear to be in the north.

And sewer overflows are not always the main problem for water quality. On some rivers and coasts well treated sewage causes most environmental problems as it still contains high levels of nutrients like phosphorus. This is often compounded by the need to abstract water from rivers for us to drink: the less water in a river, the lower its capacity to dilute sewage and the more stress on ecosystems. In other cases, such as the River Wye, the bigger problem is pollution from agriculture: pesticides, fertiliser, cattle and chicken manure.

What can the UK do about untreated discharges? 

There are basically three approaches: build bigger storm tanks to hold the sewage while waiting for capacity to treat it at sewage works (but this is expensive and carbon intensive as the tanks are built with lots of concrete, but it does work most of the time); stop the rain getting into the sewers in the first place by building rain gardens, fitting water butts, creating sustainable drainage (all termed nature-based solutions) and stopping illegal connections to sewers (these methods are less carbon intensive, better for nature and help stop surface water flooding, but they are less certain); managing the treatment works better and keeping up to date with maintenance. The current approach – led by the government and the Environment Agency – is too heavily focused on the first of these.

People can help by reducing the amount of water getting into sewers. It’s sensible to have a rain butt if you have a garden: it reduces pressure on scarce drinking water. But this will only help with sewer overflows if you’re in the right area and if lots of us do it. Having showers, rather than baths, is better, but often won’t make a huge difference (though again will save scarce drinking water). Not flushing wet wipes down the toilet and avoiding putting fat down the drains is something we can all do. But co-ordinated government action is what is needed to really solve the problem.

What should happen now? 

The problem is urgent. But it will take time to gear up solutions: there aren’t enough trained people. And we need to be flexible. Relying on the very fast installation of storm tanks as the answer could be damaging and expensive.

We ought to start from the desired outcome – clean rivers and coasts – and work back to actions. Under outcome-based regulation, water companies would be judged and rewarded for working with farmers and others to clean up rivers, not for how many sewer overflows remain. Often this would involve a different sort of nature-based solution, such as helping catchments to adapt by tree planting, stopping cattle grazing by rivers, and ‘slowing the flow’ by reinstating meanders and reed beds.

We should have started this 20 years ago when interest rates were low and it was easier to finance the work. But everyone (Ofwat, the government and the water companies) have preferred to duck the problems and keep bills low. Ofwat leadership, perhaps encouraged by government, has perhaps been the most culpable. But water companies haven’t paid enough attention to managing their assets and the Environment Agency hasn’t been pushy enough.

How much will it cost and who will pay?

We’re talking tens if not hundreds of billions in costs: the bill increases proposed recently by the water companies for the next five years are just the start. Ultimately, we will all have to cough up. But much will initially be financed by a combination of debt (borrowing from banks etc) and equity (stocks and shares, or private equity: ie stocks that aren’t openly traded, often held by pension funds).

Water companies are often criticised for paying generous dividends to investors over the past 30 years while failing to invest to stop pollution. In reality, most owners of water companies are putting some of their own money in to solve the problem and many could do more. But they do need to make a return: if a pension fund invests in a water company it needs to make enough to pay good pensions in 30 years’ time. Past owners made very tidy profits, but many of those sold the business while the going was good. And the UK isn’t as attractive to overseas investors as it once was.