Expert Q&A : Addressing the UK water crisis

Meet the Experts:

• Professor Roger Falconer FREng, Emeritus Professor of Water and Environmental Engineering at Cardiff University
• Marc Hannis, Principal, Innovation Fund at Ofwat
• David Edwards FREng, Operational Excellence Manager at Thames Water and Visiting Professor at Cardiff University School of Engineering

What are the biggest issues facing UK water infrastructure right now?

DE: It has been a long held view that the biggest challenge to the water sector’s infrastructure has been its ageing assets. There is the obvious example of Victorian mains in large cities such as London where, although incumbent suppliers can receive criticism for the leakage levels, the rate determining replacement factor often comes down to how many roads can be released for closure (without causing traffic gridlock) in order to dig-up and replace the network. The traditional intervention method has been improved upon in recent years by ‘no-dig’ technology, such as slip-lining or spray-coating. History has shown that ‘point-of-failure patching’ gains little, merely shifting the pressure to the next weak burst point, if the overall asset condition is poor.

MH: One of the biggest issues facing the water infrastructure in England and Wales right now is looking after the environment and working towards net zero. In doing this, we will push water companies to target concerns such as leakage and pollution, develop more nature-based solutions, and make sure that we have enough water available in the future, while delivering better value for money for water customers, and protecting the natural ecosystems. To tackle these challenges, we launched a £200 million Innovation Fund to drive innovative solutions to benefit customers, society and the environment.

RF: Some of the biggest challenges facing UK water infrastructure are: (i) concerns about river water quality associated with combined sewer overflows (CSOs), primarily arising as a result of a Victorian sewer system where stormwater (or rainwater) and sewage flow from domestic and industrial sources flow through the same pipe to the WwTWs (Wastewater Treatment Works); (ii) lack of an effective water grid, enabling water to be transferred readily from one part of the UK to another, particularly during drought conditions; (iii) concerns about continuing leakage from water supply pipes; (iv) poor ecological status and low environmental flows in rivers and estuaries; and (v) inadequate flood risk resilience and infrastructure.  

What are some of the engineering solutions we should be looking to?

RF: Some of the engineering solutions to address the above concerns (in the same order) are: (i) increasing use of sustainable urban drainage systems, nature-based solutions, flood protection reservoirs and increased storage capacity to reduce and/or delay stormwater flows entering a combined sewer system during high rainfall events, thereby reducing peak discharges into WwTWs and untreated sewage effluent being discharged directly into CSOs; (ii) increased upland reservoirs for extra storage and a network of pipes and more usage of canals to transfer water (under gravity where possible) from one river basin to another; (iii) increasing developments in the use of autonomous robots and fibre optic cable sensing (including duct fibres) to identify leakage locations in pipes and then repair the leak through the use of ‘No-Dig’ technology; (iv) improved management of farming practices (e.g., fencing off of river access to cattle) and better management of agricultural waste etc, together with integrated water resources design and management from input sources to sea; and (v) design of upstream reservoirs for flood control, design and construction of tidal barriers and coastal reservoirs, and better design of flood barriers etc. to protect properties from flooding.

DE: Fresh raw water resources within the UK are somewhat finite and the overall net amount is unlikely to change. The caveat to this statement comes through exploring alternative brackish and saline sources, but this comes at a cost. The Beckton desalination plant is a drought resilience reverse osmosis process that periodically abstracts from the tidal reaches of the Thames Estuary. It employs traditional sand filtration and chemical coagulation to remove solids and organics, but also uses membrane filtration technology to remove mono and divalent chemicals, hence the removal of sodium chloride (salt), making water safe to drink. The extensive use of chemicals and energy, results in the unit cost of this water being more than an order of magnitude greater than conventional treatment.

Similarly, direct reuse inevitably has to play a future part in solving the tightening supply and demand model. This is where wastewater is directly treated (without first being returned to rivers) with advanced water technologies (e.g. membranes, UVI etc) making it safe to drink. This is exactly the technology that the International Space Station uses to ensure astronauts have a plentiful supply of drinking water day in, day out.

MH: There are a really wide range of solutions that could play a vital role in future – be they innovations in technology, methodology, culture or business practices. Many of the winners of the initial rounds of the Water Innovation Competitions are already setting exciting examples for the industry. The National Leakage Research and Test Centre (NLRTC)- Northumbrian Water will create a national centre to test new products to combat leakage under “real life” conditions, improving safety and effectiveness.

The CECCU (CHP Exhaust Carbon Capture and Utilisation) – a project to turn captured carbon into useful products like paint and fertiliser, saving 5 million tonnes of CO2 per year and making the Combined Heat and Power (CHP) process – where heat as a by-product of energy generated is captured and used – carbon neutral.

How is climate change likely to impact UK water systems?

MH: Rising temperatures and drier spells due to climate change place increased pressure on water systems as demand becomes greater than supply. Additionally changing temperatures can affect water pipes and lead to leakage. Over the years, water companies have introduced state-of-the-art technology to monitor and prevent this – including advanced reservoir systems, sensors, satellites and drones, and will continue to invest in ongoing innovation to anticipate further changes.

For example, one of the winners of our Water Breakthrough Challenge 2 was the Sub-Seasonal Forecasting project, led by Thames Water, which aims to enable more accurate weather predictions for the water industry. Conventional weather forecasting gives predictions 10-14 days ahead, whereas the system being developed allows water companies to take a longer-term view and plan up to six weeks ahead to anticipate demand or potential rising mains. 

RF: Climate change is likely to impact water systems for the above concerns as follows: (i) increasing convective storms and extreme rainfall events, particularly in summer months, are likely to lead to increased stormwater flows, thereby increasing pressure on WwTWs and agricultural waste runoff (particularly animal bacteria and fertilizers) to river basins; (ii) increased upstream storage will help to reduce some of the pressures of climate change on river flooding, low environmental river flows and a desire to deliver good ecological status; (iii) potential reductions in pressure in water supply pipe systems could reduce water leakage, but this would have a limited effect, whereas sea level rise and higher surges would increase tide locking of stormwater flows into rivers and estuaries, thereby increasing flood risk to low-lying properties on floodplains etc.; (iv) increasing summer droughts would lead to lower river flows and a potential deterioration in the ecological status of rivers and poorer water quality through reduced mixing etc.; and (v) increased flood risk due to: more extreme rainfall events, sea level rise, and increased storm surges and tidal amplification. 

DE: Climate change is undoubtedly having an effect on water systems. It is manifesting itself in numerous ways.

Perhaps the best example is the deterioration of our natural raw water sources. Longer, hotter and drier summers, are resulting in a greater proliferation of algae in our surface waters. This is exacerbated by nutrient rich waters arising from organics used in agricultural fertilisers, or other waste streams, which are washed into rivers and reservoirs during catchment flushes.  Algae species comes in many shapes and forms (e.g. diatomic, filamentous etc) and they have always proved a difficult contaminant to remove, due to their buoyancy and motility. They block filters, resulting in shorter run-times and a greater necessity to backwash media, increasing process losses and ultimately producing less water into supply.

Should we be looking to reduce demand as well as improve supply?

RF: Yes, through water metering being included in all properties (domestic and industrial), new and old, and across the UK. At present there is no financial pressure on unmetered homes and business to use less water. Evidence shows that, in general, metered properties use less water.

DE: Over the recent years various statistical supply-demand models have been run. Together with immigration and internal migration, the south east faces a looming conundrum. Projection models in the Thames Valley suggest an increase in customer base of between 2–2.9 million people by 2040, three quarters of which is forecast in London. The lower end of this estimate equates to an increase of around 1.5 million people swelling the capital, which is about the same as the combined population in two of the nations larger cities (e.g. Birmingham, Edinburgh) relocating.

Supply-demand data over the recent few years has been atypical, some of which has been attributable to changing workplace behaviours, for instance more remote home working. Notwithstanding any short-term trends, combating leakage alone is unlikely to close the future gap. A successful response to this challenge, will require a multi-solution approach including reuse and recycling technology improvements, but also customer education, encouraging change of practices in embracing water efficiencies.  

MH: Thinking about our own use of water is one of the ways we can all play our part– reducing demand sits alongside reducing leakage and improving supply as the three key strands for protecting our water systems. Simple changes such as turning the tap off while brushing your teeth, or only running the wash when you have a full load, can make an enormous difference in conserving water. The water sector is investigating ways to help consumers do this – for instance Enabling Water Smart Communities is a project led by Anglian Water which takes a fresh look at how resources are used in new housing developments and focuses on how to reduce water use in the home. This includes reusing greywater (lightly used water from sinks, showers and washing machines), managing resources with new storage systems to prevent flooding, and finding new ways to treat water and wastewater.

Left to right: David Edwards, Prof Roger Falconer, Marc Hannis