Water Leakage

Water leakage is water that is abstracted, treated, or introduced into a distribution system but does not reach its intended destination because of real (physical) losses (pipe bursts, leaking joints, underground seepage, reservoir overflows) or apparent (commercial) losses (metering under-registration, data errors, unauthorised consumption). It is a central concern in urban water security and in the efficient management of supply networks.

Types of water loss

The International Water Association (IWA) water balance separates the water that does not generate revenue into two broad groups:

Real losses (physical):

• Pipe and joint failures and bursts.
• Reservoir and tank overflows.
• Leakage from service connections, valves, and fittings.

Apparent losses (commercial):

• Under-registration by ageing or poorly sized meters.
• Unauthorised consumption and meter tampering.
• Billing and data-handling errors.

Together with unbilled authorised consumption (for example, firefighting or street cleaning), real and apparent losses make up Non-Revenue Water (NRW), the water that is supplied but not invoiced.

Key indicators

• Non-Revenue Water (NRW): (volume supplied minus volume billed) divided by volume supplied, expressed as a percentage.
• Real losses per service connection per day, a metric recommended by the IWA for benchmarking.
• Burst frequency: number of mains failures per 100 km of network per year.
• Average repair time: elapsed time from leak detection to repair.

Audit methodology, step by step

1. Water balance: compile input and output volumes for each supply zone following the IWA and AWWA methodology.
2. District metered areas (DMAs): sectorise the network with flow meters and telemetry to isolate and monitor smaller zones.
3. Leak detection: acoustic correlators, noise loggers, and thermography to locate physical losses.
4. Apparent loss assessment: meter testing and replacement, anti-fraud inspections, and anomaly detection on consumption data.
5. Action plan: prioritise interventions on a cost-benefit basis, set targets, and secure financing.

Enabling technologies

• IoT sensors: pressure and flow monitoring using low-power networks (NB-IoT, LoRaWAN).
• Hydraulic models and digital twins: network simulation (for example with EPANET) to detect anomalies and prioritise renewal.
• Smart meters: frequent automated readings that flag unusual consumption and continuous flows.
• Pressure management: automatic pressure-reducing valves to lower background leakage.

Financing models

• Performance-based contracts: contractors recover their investment from guaranteed water savings.
• Sustainability-linked instruments: for example green bonds whose terms are tied to loss-reduction targets.
• Public recovery funds: in Spain, the PERTE for the Digitalisation of the Water Cycle, part of the Recovery, Transformation and Resilience Plan, mobilises around 3 billion euros for water-network modernisation (Government of Spain).

Why it matters

Reducing water leakage saves water, energy, and money at the same time, because every cubic metre lost has already been abstracted, treated, and pumped. Cutting losses lowers the associated carbon footprint, eases pressure on stressed catchments, and strengthens climate resilience and water resilience in the face of scarcity.

At Manglai we help companies measure their carbon footprint and prepare their sustainability reporting, including the environmental impact of water use and efficiency. Discover how Manglai can help you.