4 things engineers need to know to help reduce the sewage and public health problem

Sewer discharges and overflows have rarely been out of the headlines of late.

There are associated public health risks to consider, as a recent report from the National Engineering Policy Centre (NEPC) has highlighted.

The report made 15 recommendations for the water industry, covering the short-term and the long-term.

As a member of the working group that created this report, I’ve been reflecting on what they mean for civil engineers and other infrastructure professionals.

Specifically, I’ve been thinking about the role civil engineers play in protecting public health, the increasing importance of sustainable solutions, and what the sector needs to be successful in the future.

Here are four key recommendations from the report that engineers should be aware of:

1. Maintenance is not nice to have - it’s essential

Water service providers should prioritise the maintenance and rehabilitation of assets.

I daresay that every engineer knows the importance of maintenance, but sometimes it’s not as well understood by decision-makers and the public.

The report says that more planned, rather than reactive, maintenance is needed, especially as much of the network is old and arguably sub-standard.

It also stressed that maintenance programmes should align with long-term drainage and wastewater management plans.

The industry’s commitment to increasing the amount of money spent on maintenance over the next five years was acknowledged.

The report has done a good job of connecting the dots on these issues – maintaining our wastewater infrastructure system should be seen as a public health issue, as well as an environmental issue.

2. Making the best use of monitoring

Following the installation of monitors on all inland sewer overflows in England and Wales, spills from overflows are now monitored automatically.

The 2021 Environment Act also compels the water companies in England and Wales to monitor water quality upstream and downstream of discharges from overflows and treatment works.

The programme of works to install these monitors will begin in 2025.

However, what’s currently proposed to be measured, (dissolved oxygen, turbidity, temperature, pH and ammonia), provides data that’s useful from an environmental point of view, but less so for public health.

Therefore, the report called for faecal indicator organisms (FIO) monitoring to be considered.

The hope is that by studying this data, we will have a much greater understanding of the impacts that sewer overflows have on the environment and on public health.

In turn, this data could improve the current approach to bathing water standards in the UK.

As the sewerage system becomes smarter, real-time monitoring of the network and river quality will become more feasible, opening up new ways of managing the wastewater networks.

3. We can’t solve pollution problems by building more stuff

In my lifetime, the water sector in the UK has more than doubled the amount of energy it uses.

If we’re going to reduce our impact on the environment and reach net zero, we simply cannot keep doing things as we have been.

Equally true is the fact we can’t keep releasing waste into the environment in the way we have been.

This makes addressing sewage overflows and related pollution concerns and reducing carbon emissions a very difficult balancing act.

Rebuilding isn’t a viable option

The UK’s current sewer system combines wastewater and rainwater. Rebuilding the whole system would be monstrously expensive and incredibly carbon intense.

What we need to look at is how we can introduce interventions that prevent clean and dirty water from combining – returning the clean rainwater to the environment before it’s allowed to mix with sewage.

This will help mitigate the risk of the system becoming overloaded, which contributes to sewage overflows.

It would also help reduce the need for expensive and energy intensive treatment works. If the water’s not dirty, you don’t have to clean it!

Using nature-based solutions

Integrating sustainable urban drainage systems (SuDS) as part of new projects is an important way to do this, as is retrofitting SuDS where possible.

Exploring all nature-based solutions is also vital.

Working with the natural environment is an effective way to mitigate flood risk and can be a natural way to filter water.

There are also a myriad of other benefits, including cleaner air and more green space for the public.

Building new concrete storage tanks and new sewage treatment works should be the last resort.

4. The UK needs a long-term vision for water

Another key recommendation is, in a nutshell, that the UK would likely benefit from a joined-up vision for the UK’s wastewater system.

This vision should consider human health and wellbeing, the protection of nature, water supply security, flood resilience, economic sustainability, and customer satisfaction.

The ICE previously explored this at a roundtable in June 2023.

For my part, I want to build as little grey infrastructure as possible in what remains of my career.

I’m keen to focus on blue, green and hybrid solutions, instead of defaulting to grey.

I want to continue contributing to the infrastructure society and the planet needs to thrive.