The EU Leakage Reporting Deadline: What Water Utilities Need to Do Now

For most of the history of European water supply, non-revenue water was a management issue, not a legal one. The recast EU Drinking Water Directive changed that. Under Annex VI of Directive 2020/2184, large water utilities — those serving more than 1,000 m³ per day or more than 50,000 people — are now required to report water losses using a recognised methodology, submit national leakage assessments by January 2026 and from January 2028 comply with maximum leakage thresholds that the European Commission will set for each member state.

The gap between current NRW levels and those thresholds is wide. EU-wide average NRW sits at around 25%, with individual country averages ranging from under 10% in the Netherlands and Germany to over 50% in parts of Southern and Eastern Europe. Utilities that have not yet begun structured leakage reduction programmes have limited time to demonstrate meaningful progress before binding targets arrive.

What the directive actually requires

The reporting obligation is the first step. Utilities must assess water losses using either the Infrastructure Leakage Index (the ILI, which compares current losses against an estimate of unavoidable background leakage for a specific network) or an equivalent national method approved by the member state. The requirement to use a standardised metric is significant: it creates a basis for comparison and, from 2028, a basis for enforcement.

The national assessments due in January 2026 are not simply data submissions. They are intended to identify which utilities and network zones are above acceptable leakage levels and inform the thresholds the Commission will set. Utilities that can demonstrate an active leakage control programme with documented pressure management and district metering infrastructure are better placed in that assessment than those relying on annual mains burst statistics alone.

Pressure management: the primary technical lever

Of the four components of the standard leakage control framework — pressure management, active leakage control, speed and quality of repair and pipeline renewal — pressure management delivers the fastest return on investment for networks operating above the minimum technically required pressure.

The relationship is straightforward. Leakage through pipe defects and joints increases with pressure. For background leakage — the continuous seepage through hairline cracks and joint gaps that accounts for a significant share of total losses on older networks — the relationship follows a power function with an exponent typically between 0.5 and 1.5. Reducing average zone pressure by 10% will reduce background leakage by roughly 5 to 15%, depending on the network.

Active or reported leaks respond differently: reducing pressure reduces the flow rate through an open defect but does not seal it. The benefit here is that the reduced flow buys time between burst and repair, reducing both the volume of water lost per burst and the frequency with which pressure fluctuations fatigue pipe joints into new defects.

District metered areas and pressure reducing valves

The standard infrastructure for pressure management is the district metered area: a hydraulically isolated zone with a single or small number of metered inlets, each fitted with a pressure reducing valve. The PRV maintains the zone inlet pressure at the minimum required to meet service pressure at the critical point, rather than at whatever head the upstream network happens to deliver.

Simple fixed-outlet PRVs are effective and reliable, but they set pressure for the worst case. The critical point that determines the PRV outlet setting is usually the highest elevation or most remote property in the zone, and the setting required to serve that point in peak demand conditions means the rest of the zone operates at higher than necessary pressure during low-demand periods — typically overnight, when background leakage is highest.

Time-modulated PRVs address this by reducing outlet pressure during off-peak hours according to a programmed schedule. Flow-modulated valves go further: they adjust outlet pressure in real time based on measured zone inlet flow, automatically increasing pressure when demand is high and reducing it when demand falls. On networks where night-line flow is a significant fraction of total demand, the additional leakage reduction from modulating control over a fixed-outlet PRV can be substantial.

What utilities should be doing now

The January 2026 reporting deadline is close. For utilities that have not yet completed an ILI assessment, the first priority is to establish a metering baseline for each major zone — without measured inlet and outlet flows, the ILI calculation cannot be made. DMAs without inlet meters, or with meters that have not been calibrated recently, will need remediation before reliable loss calculations are possible.

For utilities that have ILI data but have not implemented pressure management, the calculation is usually straightforward. A network operating at ILI 6 to 8 — common in Southern European municipal systems — can typically achieve ILI 3 to 4 with pressure management infrastructure alone, before any pipe replacement programme is undertaken. That reduction is often enough to move a utility from non-compliant to within the range of thresholds likely to be set for 2028.

Utilities that have already deployed fixed-outlet PRVs in most zones should review whether upgrading to modulating control on high-loss zones would accelerate compliance at lower capital cost than network rehabilitation. In many cases it will.