A step-by-step guide to reduce water loss in the distribution system
Non-revenue water (NRW) is water that is produced and cleaned and then lost somewhere in the water distribution system before reaching the customer, or it can be water that for other reasons is unaccounted for. This is a global problem with NRW levels ranging from about 5% to as much as 80% in certain areas. But why is water even lost, and what are the options available?
10 steps to beat the leaks in water systems
1. Aim for efficient leakage recovery
One of the primary causes of water loss is leaking pipes and equipment due to bursts or breaks. It is not an easy task to locate a leak in a huge distribution network, and it can take days, weeks or even years before a leak is even noticed. Therefore, preventive activities and efficient leakage management is essential.
2. Divide the distribution network into sections
If you try to cope with water losses in the whole distribution network at once, you will need to work in a reactive, passive manner, where activities are initiated only when a water loss becomes visible or is reported.
An efficient technique to obtain an overview of what is going on below ground, is to divide the supply network into sections, also referred to as district metering areas (DMAs). Water loss can then be calculated for each section, and operators are able to better plan and prioritise their efforts.
3. Fast assessment and repair
Operators can act more efficiently, when the network is separated into DMAs. Immediate action can save vital resources and will cause less disturbance for network customers, who depend on a continuous water supply.
By investing in a targeted leak detection program, it will in most distribution systems be possible to reduce the overall leakage by at least 40–50%.
4. Monitor network activities
Leakages can easily be detected through noise loggers integrated in e.g. ground-level surface boxes. The loggers react to the sound of leaking water and enable operators to act immediately.
It is also possible to measure and manage water pressure in the different areas of the supply network by using the technique of DMAs.
5. Pressure management
Pressure management is considered the single most beneficial, important and cost-effective leakage management activity. The higher the pressure in the distribution network is, the more water is lost through bursts or leakages in the network. Furthermore, most pipe bursts occur due to ongoing pressure fluctuations forcing the pipes to continuously expand and contract, resulting in stress fractures.
Control valves maintain a certain pressure, flow or level regardless of changes in the supply network. They are essential for pressure management, as they can assist in reducing water losses while upholding the best conditions for the network equipment.
Pressure management is also an efficient way of reducing unnecessary energy consumption. The pressure can be adjusted to the critical point at a strategic consumer in the DMA, meaning that energy will not be spend on pumping water to a higher pressure than necessary. Also, by allowing for a lower pressure in general, especially during off-peak hours, energy consumption for pumping can be reduced.