NRR: THE KEY TO LEAKAGE-DRIVEN ASSET RENEWAL
Dennis Grimshaw, RPS Water
(free)
Most water companies in England and Wales are currently operating at, or in some cases
below, economic levels of leakage. However, there may be future pressures to reduce future
leakage targets as a result of more comprehensive inclusion of the environmental, social and
carbon costs in the ELL calculation process.
Because of the poor serviceability of the network infrastructure in some areas, leak detection
and repair, as a leakage control policy may not be cost effective in either maintaining current
levels of leakage or achieving further significant reductions in leakage, unless augmented by
increased levels of asset renewal.
The relationship between asset renewal and leakage carries a high degree of uncertainty.
Nevertheless, it is perhaps surprising, given the high profile of leakage, that the current
basket of asset serviceability indicators does not include any measure of leakage.
The “Natural Rate of Rise” in leakage (NRR) is an important parameter in leakage economics
and measures the growth and breakout of leaks. NRR provides the link between operational
leakage management and other capital-intensive leakage control policies involving renewal of
assets. It therefore has the potential to provide a role as an asset performance indicator.
The paper includes examples illustrating the application of NRR as a means of comparing the
cost-effectiveness of alternative leakage-driven asset renewal policies to active leakage
control involving traditional leak detection and repair.
KEY WORDS
Investment Planning, Mains Renewal, Leakage Economics, Natural Rates of Rise in Leakage.
