Heriot-Watt University (HWU) in Edinburgh, Scotland is globally recognised as the leading expert in drainage solutions. We asked Dr Michael Gormley, Associate Professor at the Institute for Sustainable Building Design, for his perspective on the challenges the world faces on World Water Day.

Dr Michael Gormley, Associate Professor at the Institute for Sustainable Building Design at Heriot Watt University.

This year’s World Water Day has a global warming theme and, rightly so, given that climate policy makers must put water increasingly at the heart of their action plans. Yet this year’s event also comes as the world confronts what is the biggest public health challenge of the new millennium too: the coronavirus pandemic.

As we get to grips with these twin, grand challenges, World Water Day is a timely moment to reflect on how population and industrial growth are adding new sources of pollution and increased demand for clean water with the public health challenges arising from this. As a result of climate change, for instance, it is estimated that some 1.8 billion people will live in countries by mid-decade with absolute water scarcity.

Take the example of cities which, as they get larger across much of the world, and buildings often larger and taller, there is increasing strain on systems to protect public health and optimise resource management, including water supply. Much current-day building design guidance and standards, whose basis dates back to seminal work carried out in the 1940s in the United States, are simply not fit-for-purpose to meet our twenty first century challenges.

The way people use water systems, for instance, is fundamentally different from that mid-twentieth century era, and daily per capita consumption is increasing. This is putting growing pressure on urban resources, including from wastewater disposal in buildings.

And the climate agenda is a real concern here too as we must move also toward ‘net zero’ emissions, especially in construction. With the built environment and construction responsible for a staggering 35%-40% of global CO2 emissions it is easy to make the case that everyone involved in this industry needs to do their bit.

Now is therefore the time for key players across the public and private sectors, including regulators, academia and industry, to look again at building design, especially high rise, to be much more flexible and agile. Industry has a fundamental, legitimate role in this process, including innovation around how current rigid building codes and standards need reform.

Take the example of piping for wastewater in high rise buildings, with increasing innovation around different size pipes to increase capacity and use less water. Current codes and standards make such innovation difficult, despite scientific understanding of the benefits.

I am pleased to say that Aliaxis is one of the industry players at the fore of this debate, looking not just at codes and standards in general, but specifics like finding better ways to carry away waste in piping safely and efficiently. This is a critical issue for health and disease prevention.

One concern relating to wastewater systems within tall buildings is the management of air flow and air pressure. The flow of air, induced by wastewater flow can lead to water trap seals being lost due to negative (suction) pressures or positive (blowing) pressures. This results in a loss of protection for inhabitants from contaminated air from the sewer.

The sewer is a reservoir for pathogens and so protecting water trap seals, still the main protective device in the system, is an imperative. Balancing system pressures is therefore central to protecting public health. Technology, design and appropriate codes and standards all play their role in doing this important job.

The challenges of global warming have often been described in terms of balancing too little water and too much water. In building terms, roof drainage illustrates the problem well.

High intensity rainfall is associated with global warming and specific technology and design approaches are needed in this area. Siphonic roof drainage offers the advantages of reduced materials but is tuned to only one rainfall intensity event. Scientific advancement in this area has improved the design and implementation of these systems over conventional gutter and downpipe systems.

Roof drainage also offers opportunities for harvesting water for re-use with buildings. This has the dual impact of providing a resource to be used in the building, but also attenuating the flows that could lead to flooding events in urban settings as stormwater drains overflow.

We need to better ‘harvest’ this precious resource. It is one of the key messages of the UN on World Water Day.

Taken overall, this is a huge agenda and everyone has to play their part. We need not just immediate action, but also a longer-term range of reforms.

The challenges to realising this agenda are real, but if we can surmount them, the prizes will be more sustainable cities, better public health, and the prospect of mitigating climate change pressures. On this important World Water Day moment, will we seize the opportunity, or let it slip?