Towards a ‘gold standard’ for sewer safety and climate resilience:

At the World Water Summit 2024  in London, held from the 15th to the 17th of April,  a round table discussion was held on the topic of  the “gold standard for sewer safety”. This topic was also the subject of a white paper published in May by Global Water Intelligence in partnership with Grundfos.  

Every year, according to C40 Cities – a global network of cities working on climate resilience -  water system failures cost public authorities more than U.S. $ 200 billion. Included among the water system issues frequently encounterd by cities are sewer overflows, a problem that is currently increasing with the increased intensity of rainfall events caused by climate change, and exacerbated by the gradual deterioration of urban wastewater infrastructure that takes place over time except in situations where fairly substantial amounts of capital are invested in upgrading and climate proofing the network.

As the white paper points out, public frustration with sewer overflows has been expressed in some very well known urban locations such as the Thames River, Sydney Harbour, and Lake Michigan. The (double) goal of the white paper is to provide a perspective on the scale of the challenge as well as to offer innovative and cost-effective solutions for more resilient water infrastructure. In fact, the ambition of the paper is not only to benchmark resilient sewer infrastructure but to set a ‘gold standard’ for industry practices.

In this context, Ralph Exton, Vice President of Grundfos, who announced the launch of the white paper, stated that the document is intended to become a reference for professionals and a source of actionable information on best practices and tools for building resilient networks and liveable cities.

The authors present the urgency of sewer security from the triple perspective of climate, social issues and economics. In the realm of climate change, sewers are both a cause and effect of climate change, as they contribute to emissions and are also regularly put to the test with high intensity precipitation events, which threaten to increase sewerage releases into the environment. Furthermore, as a result of increasing water scarcity, wastewater is being seen more and more as a resource to be treated and reused.

Socially, the authors point to public frustrations with pollution caused by sewerage overflows and leakages, with utilities running the risk of being perceived as more concerned with profitability than with service to customers. Public interest in swimmable rivers and the benefits of ecosystem services for liveability are inducing local leaders to seek lasting solutions.

In economic terms, the cost of completely replacing existing infrastructure induces the sector to seek economically sustainable solutions, while recongising that responding to sewerage spills also comes at a cost.

The aim of a ‘gold standard’ for sewer security refers to at least three dimensions of aspiration : firstly, the aim to achieve zero spills as an ultimate target, even if this is very difficult to achieve in practice, with a focus on the impact of pollution on water quality (SDG target 6.3). Secondly, the gold standard requires that utilities are involved in public engagement, such that public perceptions of utilities are shifted from that of polluters to one of protector. Finally, the gols standard needs to embrace broader social and environmental goals, incorporating the co-benefits for society and the environment within the overall vision for sewer management. 

To achieve this gold standard, sewer security needs to dispose over a range of tools in its toolkit. For example, this includes prediction and prevention tools : making use of sensors and software analytics to detect blockages and pump failures in advance. Similarly, automation and optimisation can be engaged by integrating weather forecasting and real-time optimisation of the storage capacity control to minimise negative impacts, while exploring options to increase existign wastewater treatment capacity.