Africa’s “hidden dams”, in the form of non-revenue water (NRW), exist underground in leaking pipes beneath streets; and in the financial pressure they place on municipalities. NRW – the share of treated water that is lost before it reaches or is billed to customers – represents one of the fastest, most practical ways to stabilise water supply across the continent, writes Sean McCormick, GIBB Specialist Engineer in NRW Reduction. 

In a context of intensifying drought cycles, rapid urbanisation and constrained public budgets, reducing these losses is necessary to ensure economic resilience and service delivery.

Water security in Africa means reliable, continuous access to safe drinking water. But, for many communities, this remains out of reach. Even in relatively well-served countries such as South Africa, systems are increasingly strained as cities expand faster than infrastructure can keep up with. The result is intermittent supply, falling pressure and, in some instances, system failure. NRW is key to this challenge, as not dealing with it leads to a reduction in available supply of water to consumers and negatively impacts the financial viability for municipalities.

Essentially, NRW includes all water lost between production and consumption. This takes two main forms: Real losses, such as leaks from pipes, bursts and failing infrastructure, which are mostly visible, and Apparent losses, which are just as significant, that is, water that is consumed but not measured or billed due to faulty meters, data gaps or unauthorised use. In many African cities, NRW exceeds 30% of total supply and can reach as high as 60%. That means more than half of treated, energy-intensive water never generates value.

This is why NRW is often coined “the most expensive water of all.” Utilities have already paid to abstract, treat and pump it, often under tight electricity constraints, only to lose it underground or on paper. The consequences are compounding. Reduced revenue limits a municipality’s ability to maintain infrastructure, which leads to more leaks, higher losses and further financial strain. This is a vicious cycle that, if left unhindered, can push systems toward collapse.

Against this backdrop, large-scale infrastructure projects such as new dams, transfer schemes or treatment plants, remain necessary but insufficient. They are capital-intensive, slow to deliver and frequently constrained by environmental and regulatory hurdles. NRW reduction, by contrast, can be deployed immediately and scaled incrementally. Every litre saved is effectively “new water” made available without new abstraction.

The engineering case is straightforward. Pressure management, for instance, is one of the most effective tools for reducing real losses by lowering stress on pipes, reducing burst frequency and limiting background leakage. With modern pressure technology, system pressures can even be adjusted dynamically, lowering pressure during off-peak hours when demand is low and reducing losses further.

Equally important is measurement. Many utilities still lack accurate data on how much water enters and moves through their systems. Improving network and customer metering and maintaining reliable billing systems are important first steps. Without measurement, there is no diagnosis and no meaningful intervention. In this respect, NRW reduction is as much about information as it is about infrastructure.

The economic implications are substantial. A 10% reduction in NRW on a national scale can translate into billions of Rands in savings and additional revenue. For water service providers, this improves cash flow, reduces the cost of bulk water purchases and creates space to reinvest in maintenance. For communities, it means fewer supply interruptions and more reliable access. For economies, it supports industrial activity and investor confidence, particularly in water-dependent sectors.

That said, NRW programmes often falter not because the solutions are unknown, but because they are not sustained. Leadership changes, competing budget priorities and the failure to ring-fence savings can undercut early gains. NRW management is not a once-off project; it is an ongoing operational discipline. Success depends on consistent monitoring, reinvestment and institutional commitment.

The priority should be to focus on the systems Africa already has. In a resource-constrained environment, the quickest path to water security is improving what already exists. Africa’s “hidden dams”, that is, the water already produced but currently lost, offer an opportunity to drive a scalable, engineering-led intervention capable of delivering immediate returns. And the time to do it is now.