It often surprises people to learn that all the water on earth today has been around for over 4 billion years. The water cycle is a ‘closed system’ – this means the water dinosaurs drank is the same stuff that comes out of your tap, purified by the process of changing states through evaporation, condensation and freezing. Although modern technology has come up with ways to ‘make’ water, it is an incredibly difficult and unsustainable process requiring plenty of energy - which coincidentally also needs plenty of water to produce.
Unfortunately, contemporary practices continue to over extract and pollute drinking water resources; the Environment Agency warns that the Southeast of England could run out of fresh water in 25 years. It is no surprise then that there’s been a dramatic increase in public awareness about sewage dumping practices in the UK. The movement to keep our waters clean has been championed by celebrities like The Undertones lead vocalist Feargal Sharkey, and activist groups like Surfers Against Sewage.
It is a rare and exciting event when the public succeeds in influencing policy decisions. This is exactly what happened on 9 November, 2021 in the UK. Media and public outcry pushed the UK Parliament to revisit and approve amendments to the 2021 Environment Act which had been previously rejected. The amendments were designed to increase the accountability of private water companies. Specifically, amendments to Sections 81 and 82 of the Act address issues of wastewater management plans, calling for a reduction of sewage overflow contamination, increased transparency, monitoring and progressive actions to lessen the impact of sewage on water quality throughout the UK. The Act has led to several avenues for to address these issues. One solution - infrastructure improvements - is luckily close to realisation in London. Prior to the act, a £5 billion investment was made to build the Thames Tideway Tunnel, an ambitious infrastructure upgrade that promises a 95% reduction in sewage discharge events, set to be operational within the next year.
However, there remain several political, financial and technological barriers to taking further action towards the goal of reducing sewage contamination. In fact, deadlines to achieve clean water targets have passed without being met. Specific barriers include a lack of technology to monitor the impact of sewage overflows. This means we will have insufficient baseline data to measure the effectiveness of the Thames Tideway Tunnel once it becomes operational.
The Thirst monitoring network is the first initiative of its kind to address these knowledge gaps. As part of it, low-cost water quality sensors have been installed at sewage overflow sites in the tidal Thames to log data for a baseline of water quality in the Thames. This effort was initiated in the Department of Geography at King’s in 2023 with support from Dr Kris Chan and Professor Michael Chadwick. Dr Kate Olde and Nathan Oo at the John B Thornes Lab helped develop the sensors in the makerspace here. The Thirst water quality sensors built through this effort can meet freshwater and estuarine environmental monitoring goals proposed by the Department for Environment Food and Rural Affairs (DEFRA) in the 2023 Event Duration Monitoring initiative.
Importantly, the Thirst sensors are built on open-source technologies and have been developed at a fraction of conventional costs. These two features allow for their use by a wide range of stakeholders, including both regulators and private water companies. The simple design means that these sensors can be built and maintained by non-professionals, allowing the public to contribute through citizen science.
Alongside sensor feeds, the results of manual testing are being used to develop a contaminant prediction model, leading to the possibility of real-time data processing at an accuracy rate of 70%. Adjustments to the sensors and prediction model are ongoing but the potential for these tools to inform and address issues of pollution accountability is promising.
Watch documentary
This short documentary by Dr Randa Kachef shares the stories of Londoners who are doing their bit for the Thames.