Across England and Wales, a vast and critical infrastructure lies hidden beneath our streets and gardens: the sewer network. Yet, a staggering 155,000 miles of this network remain unmapped, posing significant challenges to water companies tasked with maintaining and managing these essential systems. WRc Principal Consultant Peter Henley delves into the technological advancements that are beginning to shed light on these previously unknown sewer systems, offering a glimpse into a future where effective maintenance and proactive management could become the norm.
The invisibility of these sewers presents a myriad of issues. Blockages, pollution incidents, and collapses are not only more difficult to respond to but also more challenging to prevent. Currently, water companies rely on reactive mapping, sending teams to investigate and map sewers only when blockages are reported. At the current rate, it would take 80 years to map the entire unmapped network—a timeline that is simply too long given the escalating challenges of climate change and the anticipated housing boom. As Henley points out, “80 years is a long time: too long to enable us to effectively manage the challenges facing us now and which will only get worse as the impacts of climate change are felt in the UK.”
Enter advanced technology. Over the past few years, businesses like WRc have been exploring innovative methods to map these sewer systems more efficiently. One such method involves using aerial photography to identify manhole covers and infer the routes of sewers beneath roads and gardens. Modern aerial cameras can capture images with such high resolution that they can identify objects as small as a mobile phone on the pavement. This technology allows for large areas to be quickly captured, providing a detailed picture that can be used to identify manhole covers and suggest sewer routes. However, it’s not as simple as connecting the dots; manhole covers also provide access to other utilities like electricity, gas, and internet cables. Therefore, interpreting these images requires a deep understanding of the sewer system and the types of houses and their known infrastructure. According to Peter Henley, “Aerial photography advances enable a large area to be quickly captured with a picture quality sufficient to identify manhole covers and suggest the route of the sewer. It is not as easy as a simple dot-to-dot exercise.”
WRc has already demonstrated the feasibility of this approach through a pilot programme for Thames Water. By studying aerial photography and applying their expertise, the team successfully mapped three 1 km2 areas with an 80–90% success rate. This research underscores the potential of this technique, but it also highlights the current reliance on human knowledge and experience. To truly scale this solution, WRc and its RSK partners are exploring how to train an AI solution to automate the digitisation process. This would enable engineers and data specialists to focus on reviewing and ensuring the accuracy of networks, speeding up the process and improving its accuracy. The technology is certainly there; we now need to venture into the unknown and make it a reality.
The implications of this technological leap are profound. As Henley notes, “Currently, when a water company receives a blockage call out, if the sections of sewer involved are unmapped, they will need to send their teams to investigate and while there, the engineers will map these sewers and incorporate the maps into their own records.” By automating this process, water companies could respond more quickly and effectively to blockages, reducing the incidence of pollution and collapse. This shift would not only improve the efficiency of maintenance but also enhance the overall resilience of the sewer network in the face of climate change and increased urbanisation.
Moreover, the ability to map these sewers more efficiently could revolutionise how we approach infrastructure development. With a clearer understanding of the sewer network, urban planners and developers could design more sustainable and resilient systems, reducing the risk of flooding and pollution. This could also pave the way for more innovative solutions, such as green infrastructure and sustainable urban drainage systems, which could further enhance the resilience and sustainability of our cities.
As we look to the future, the potential for AI to transform the water, sanitation, and drainage sector is immense. By harnessing the technical domain knowledge held by specialists, we could create AI solutions that not only map these unseen systems but also predict and prevent issues before they occur. This would represent a significant shift in how we manage our infrastructure, moving from reactive to proactive maintenance. However, this journey is not without its challenges. As Henley acknowledges, “There is still a great reliance on human knowledge and experience to turn these aerial photographs into usable references for the networks. That process is still intensive to truly scale this as a solution.”
The water, sanitation, and drainage sector is at a crossroads. The challenges we face are daunting, but the technological advancements we are witnessing offer a beacon of hope. By embracing these innovations and pushing the boundaries of what
