Untreated waste regularly flows into waters across England and Wales. Is it time to radically rethink sewage – or do away with sewers altogether asks the Guardian.

Raw sewage in British waters is more than simply the horror of swimming amid human waste but also about the health and environmental threats of microplastics, endocrine disruptors, phosphorus, antibiotic-resistant bacteria and even Covid-19.

Although few Britons think about what happens when they flush their toilets, it likely involves a combined sewer network, fed by rainwater – including road and land runoff – and buildings’ waste drains.  On good days, wastewater flows to the sewage treatment works, where it undergoes filtering, dewatering, processing and recycling.

But good days are increasingly rare. Previously, only freak storms would fill the system to the point that the sewage-rainwater soup would spill out into waterways via combined sewage overflows (CSOs), to avoid the even grislier prospect of it spouting back up our drains. Now, however, both the number of houses and the frequency of storms have increased. The system is so far over-capacity that in some areas drizzle can make it overflow – exacerbated by blockages and ‘fatbergs’ which can cause CSOs to spill even when it’s not raining.

All overflows reach the same place: “All of our waterways are connected … It’s one cycle: what goes into our rivers ends up in our ocean ….  Despite the progress that investment has made, we still see thousands of sewage pollution events each year emanating from the CSOs on our coastline, and particularly in our rivers.”  Evidence to the Environmental Audit Committee indicates that raw sewage breaches in UK rivers 10 times greater than estimated by the Environment Agency.  “ … many of the treatment works do not continue to treat a minimum rate of sewage when they are spilling and many of these illegal spills are not identified by the EA”, MPs on the EAC were told.  Click here.  Earlier this year, Defra announced additional new measures to reduce harm from storm overflows to be made law.

Hard engineering alone is not a feasible solution. “You can’t typically invest your way out of it by enlarging sewers, pouring lots of concrete and having big tanks. That costs an awful lot of money, and it contains a lot of embedded carbon …. We’re looking at a move towards more green infrastructure, that slows surface water or prevents it getting into the sewers,” says the Environment Agency.

A key example of green infrastructure solutions are sustainable drainage systems (SuDS).  SuDS are intended to mimic nature and typically manage rainfall close to where it falls before it enters watercourses and overwhelms combined sewage systems. Designed to transport surface water, attenuate runoff, provide areas to store water in natural contours, to enable water to soak into the ground or evaporate from surface water or be taken up and transpired from vegetation, SUDS are intended to be environmentally beneficial, causing minimal or no long-term detrimental damage, for which design and evaluation guidance is available.

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