Best practice NRW management is based on the principle of breaking down the distribution system into smaller and more manageable units known as District Metered Areas (DMAs), where the flow balance can be monitored for each DMA.

Ideally, a hydraulic model is used to optimise the design of the DMAs, where several considerations are applied, such as minimum detectable leakage volume, pressure balancing across the DMA, grouping of customer categories and security of supply. This can be done in each DMA or in groups of DMAs by clustering the DMAs into Pressure Managed Areas (PMAs).

Pressure management is a core pillar of active leakage management. However, long-term and ongoing control is necessary, and integrating NRW efforts into day-to-day operations is key to success. Aside from conducting annual water audits to identify potential areas for improvement to be included in the NRW master plan, the focus during the operational phase should continuously be on:

• Regular analysis of the NRW level based on the water balance in each DMA.
• Optimisation of the DMA performance based on ILI and ELL for each DMA.
• Installation of new technological advances to ensure a continuous improvement and expansion of reliable data from the distribution system.

Smart pressure management

A smart water system consists of multiple components such as intelligent pumps, intelligent valves, smart meters, deployed noise loggers, acoustic leak detection and much more.

As an example, pressure management is implemented via the use of intelligent pumps or intelligent valves, depending on whether the specific PMA or DMA is to be subject to a pressure increase or a pressure reduction. In extreme cases, some areas may be subject to a combined solution to cater for all operational scenarios.

As the demand for water varies widely throughout the day, controlling the inlet pumps or valves supplying the individual area will reduce the existing background leakage, frequency of new pipe bursts and optimise energy usage. This is implemented by regulating the pressure supply to a level that secures the minimum guaranteed pressure at the critical point, thus securing an adequate pressure at each customer connection throughout the day.

High-quality materials ensure a long lifespan

PE pipelines with an estimated durability of 80–100 years are used for all new water distribution networks and service pipes in Denmark.

Once equipment has been installed below ground as part of the distribution system, it is very difficult to control the valves, pipes or other installations. Therefore, it is important that all equipment and installations are of high quality to ensure that they will function properly for many years.

In addition, welding and making joints of the PE pipes must be carried out by well-educated staff in accordance with quality standards to ensure a correspondingly long network lifespan. To achieve the optimal conditions for NRW reduction, only quality products with a long warranty, reliable and durable function should be selected.

Rather than choosing products simply based on the initial purchasing price, products should instead be chosen based on the principles of Total Cost of Ownership. A generally accepted norm is that the purchasing cost for a pump is only 5 percent of the total cost of the pump’s lifetime, where 10 percent accounts for maintenance costs and the remaining 85 percent goes to energy costs related to operating the pump.

Similarly, by choosing shut-off valves of high quality, leakages from the valve itself can be avoided, and gate valves with high-quality rubber gaskets ensure that the valves are 100 percent drop tight.