Melaka is a relatively small state on the southwest side of the Malay Peninsula with a city so rich in history and beauty that it is listed as a UNESCO World Heritage site. With a population around 850,000, the Melaka Water Co. Limited (SAMB) manages roughly 270,000 service connections for commercial and residential customers.
In 2008 the city embarked on an aggressive plan to upgrade their water infrastructure in order to reduce the non-revenue water (NRW) loss. Leakage rates were at 33.9%, accounting for 152,000 cubic meters of water loss per day, which is 55.6 million cubic meters per year. With 4,800 kilometers of aging pipelines, pipe bursts were just under 3,000 per year. Each pipe burst compounded the water loss problem until crews arrived, and with so many occurrences, maintenance teams were constantly in reactive mode.
“It was clear the current situation needed to be fixed, but our long-term vision was equally important and so we implemented a massive overhaul that would not only fix our problems today, but give us a long-term sustainable plan for population growth,” says Datuk Ir Haji Mohd Khalid Bin Haji Nasir, CEO of Melaka Water Co. Limited, Malaysia.
Singer Valve Malaysia was called in to work with the city’s NRW team to help select and advise on a range of diaphragm-operated automatic control valves to assist Melaka in implementing their District Metered Area (DMA) plan. “Pipe bursts and leakage rates are directly affected by water pressure and the selection of the pilot operated control valves required is a crucial part of any NRW plan,” says Anand Anandarajah, director of operations for Singer Valve Malaysia. “Using DMAs to reducepressure is the most immediate and cost-effective approach to dealing with NRW losses.” After completing a water audit, it was determined that 168 DMAs needed to be established to manage the entire utility’s distribution system.
The DMAs enabled the utility to measure the overall flow in and out of a zone, and with the help of calibrated meters, the team could then determine the most challenged zones that needed serious attention with infrastructure replacements. The second part was to manage the pressure in each zone to supply exactly the right amount of pressure that customers in each DMA required. For every 1% increase of pressure, the leakage rate goes up by 1.15%, so maintaining the right pressure iscrucial. It is also typical for demand to fluctuate between night and day, causing the pressure to fluctuate, which the pressure-reducing valve (PRV) needs to accommodate for.
SAMB put in a combination of 138 pressure-reducing and altitude valves that ranged in size from 100 millimeters to 200 millimeters to provide a consistent flow in each DMA as required by their users. The PRVs and their associated pilot systems sense the downstream pressure through a connection at the valve outlet so that when the pressure changes, the downstream pressure set point remains constant. This controls the valve position by accurately controlling the chamber above the diaphragm, ensuring that the downstream pressure is maintained steady at the set point regardless of fluctuation in flow or upstream pressure.
In numerous DMAs where upstream pressures range between 3–4 bar, the Singer 2 PR SC BT was used to reduce the required downstream pressure of 1.5 bar in the day and 1 bar at night by a simple switch between day and night utilizing a battery timer and two pressure set points. The battery timer in conjunction with a latching solenoid allows downstream pressure to be selected based on time requirements and utilization of two pressure-reducing pilots. One controls nighttime pressure downstream of the valve (1 bar), while the other controls daytime pressure downstream of the valve (1.5 bar). The units utilizing the battery timers are typically used when more precise control is required beyond that of a normal PRV. This can significantly reduce water loss by giving two pressure options instead of one. They can also be retrofitted easily to an existing PRV, should the requirements change.
Melaka’s older style level valves had also become inaccurate and allowed reservoirs to overflow, wasting water and increasing NRW. To fix this, they were replaced with altitude valves that are used to control the maximum levels of the reservoirs and accurately control the draw down of the reservoirs before refilling. This new level control technology with altitude pilots now accurately controls the levels repeatedly and dependably with minimal maintenance.
The end result is that pressure leakage has been reduced from 33.9% to 21.4%, which is a total savings of $5,232,857 per year. Pipe bursts are down by 93% from 3000 to 200 per year and reservoirs are maintaining their desired levels of water without overflowing, which will help delay water rations in the dry season. By managing water pressure, Melaka was able to realize some significant savings so they can now provide more connections—and with a 36% increase in revenues, upgrades to infrastructure is a manageable part of operations. The utility also updated their GIS and network modeling for monitoring the flow of the entire distribution system at all times, so that crews are now able to schedule proactive maintenance.
These amazing cost savings and results were recognized by two Federal Government awards, one for green technology in reducing NRW loss and the other for the improvements to the entire system. “We have dramatically increased the lifespan of our water assets and we are now confident that we have an efficient consistent delivery of quality water for all our residents,” says Nasir.
Editor’s Note: Though this case study takes place in Southeast Asia and shows a very dramatic leakage and water loss rate, aging US infrastructure is also contributing significantly to leakage and non-revenue water. Pressure-reducing valves can be of value in solving the problem for some municipal systems and some US water providers may find a model in this project. Non-revenue water and water shortages may well be the hottest topics in water right now. The American Water Works Association has created a water loss control resource community that can be accessed here.
