Pressure management is the control of pressure in a water network to cut leakage and bursts while keeping enough pressure for customers.
Pressure management is the practice of keeping pressure in a water distribution network no higher than needed, to reduce leakage, bursts and wear, while still giving customers and fire services the minimum pressure they need. Leakage rises with pressure. The link is often described with the N1 power law: L1 / L0 = (P1 / P0)^N1, where L is leak flow, P is pressure and N1 is an exponent. For a fixed round hole N1 is about 0.5, while for leaks that open wider under pressure, such as splits in plastic pipes, it can reach 1.5 or more. In mixed networks a value near 1 is often used as a first estimate. The usual tool is a pressure reducing valve (PRV) at the inlet of a district metered area. A fixed-outlet PRV holds one set pressure. A time-modulated PRV lowers pressure at night, when demand is low and pressure would otherwise rise. A flow-modulated PRV adjusts pressure with demand, using a controller linked to a flow meter. Where water is pumped straight into the network, variable speed pumps can do a similar job. Example: a DMA has night leakage of 10 m³/h at an average pressure of 60 m. Lowering pressure to 45 m with N1 = 1.0 gives 10 × (45 / 60)^1.0 = 7.5 m³/h, a cut of 25%. With N1 = 0.5 the new leakage is 10 × (0.75)^0.5, about 8.7 m³/h. Lower and steadier pressure also means fewer bursts and can extend pipe life. Limits: pressure must stay above service standards at the highest and farthest points, and fire flow must be checked. PRVs need regular maintenance and can fail or cause surges. Lower pressure can reduce customer use and so billed volume. In intermittent supply, the aim may be to even out pressure rather than to lower it.