The Zen Of Smart Pressure Management: Calming Water Distribution Networks
By Andrew Burrows, Chief Technology Officer, i2O Water
Over recent years, water companies around the world have enhanced their ability to control the pressure of water in their distribution networks to improve customer service and achieve environmental savings.
For water companies, the ease by which water passes through the network can make a huge difference to their customer experience. Insufficient pressure caused by high flow at times of peak demand generates customer complaints. Boosting pressure to fix these customer service issues can have a significant negative impact on leakage levels, burst frequency, and energy consumption.
Aging water distribution networks are rarely a smooth ride. Being able to successfully deliver huge amounts of water into a city and provide adequate supply to far-flung communities is a significant historic engineering achievement.
With growing water scarcity, population growth, and increased economic activity, ensuring sufficient pressure to keep the taps on remains an everyday challenge for water companies. Most networks are a massive distributed mesh where flow can be constricted by varying pipe diameters and legacy engineering technology. Corrosion and sediment are common problems, creating friction that constrains the smooth flow of water to each and every customer.
Traditionally, pumps or pressure-reducing valves (PRVs) would be set at an increased water pressure to compensate for frictional flow loses. The target pressure would be set to ensure adequate customer service for all at times of peak demand.
During periods of low water demand, however, high levels of pressure in the network would place pipework under significant additional stress. High levels of leakage and increased burst frequency were an unfortunate byproduct of ensuring there was sufficient pressure to satisfy customers during peak hours.
Simple solutions to this problem involve manually scheduling pressures according to time of day, but these can cause problems when pressures are increased ahead or behind actual demand by generating pressure volatility and surges in the network that cause bursts and water quality problems. Manual calculations lead to conservative target pressure setting that unnecessarily stresses the network.
Facing scarcity challenges, regulatory scrutiny, and high levels of energy consumption — typically a huge operational cost — the most advanced water companies have started using data, analytics, and automated systems from firms like i2O Water to optimize how they control pressure in their networks.
Water companies can now monitor flow rates and associated pressure variation in their network to learn the relationship of pressure with differing patterns of customer demand. This then allows them to automatically adjust pressures to meet changing patterns of water demand, achieve a calm network, and minimize the excess network stress that drives up leakage and burst frequency.
An implementation of i2O technology at Manila Water’s N. Domingo Pump Station in the Philippines has yielded impressive results. The region it serves includes areas of high elevation, requiring pumps to maintain specified pressure levels to deliver a constant supply of water. It serves a wide range of domestic and commercial customers, including hospitals, hotels, schools, and colleges, and experiences highly variable demand for water. Flows range from 40 liters/second (l/s), or 634 gpm, at night to 175 l/s (2,774 gpm) during periods of peak demand.
By using smart pressure management technology to automatically adjust pump settings, Manila Water has maintained a stable target pressure to the customer and removed excess pressure from managed zones. Since the implementation it has achieved target service levels 99.8 percent of the time (up from 88 percent previously), reduced leakage by 18 percent, and achieved energy savings of 283 kWh per day at its pumping station.
In the UK, Anglian Water wanted to find more intelligent methods for controlling its pump-fed zones and decided to trial i2O technology in four district metered areas (DMAs). Following a period of flow and pressure data logging, it used automatic optimization and remote control functionality, successfully reducing average zonal pressures by 16 percent.
Optimizing pressures and calming pressure fluctuations reduced daily inflow by 4 percent, cut energy usage by 8 percent, and resulted in improved customer service levels. The project extended the lifetime of mains and service connections and delivered a complete return on investment in less than eight months.
Following the success of this initial work, Anglian Water has engaged i2O to implement smart pressure management technologies across its wider network as it seeks to reduce leakage by more than 20 million liters/day (5.28 MGD) and cut the time it takes to restore service in the event of an interruption from 19 to 12 minutes on average.
The success of these and similar projects relies on being able to calm the fluctuations in pressure and flow. Understanding how demand changes over time, how this impacts pressure and flow, and putting in place the ability to continuously and automatically adjust pump and PRV settings to ensure supply precisely matches demand, removes the excesses that stress the network, and increases leakage and burst frequency.
Pumping less water at a lower average pressure reduces water wastage and also — in pump-fed zones — energy consumption. Typically we find that customers are able to reduce pumping pressures by 20 percent on average through optimization, which in turn is enabling them to achieve energy savings of more than 30 percent.