Detection and calculation

What is top-down leakage calculation

Water produced - total known water consumption = leakage losses

• Taking into account all metered and unmetered consumption, estimations of flushing and known inaccuracies in measurements.

• Useful for comparing against the PCs and Ofwat leakage targets

What is bottom-up leakage calculation?

Estimates leakage through measurement and detection on a local scale;

• DMA monitoring

• Minimum night flow analysis

• Step testing

• Correlation etc

Used to find and fix leaks to achieve the targets that top-down finds

What effects can demographics have in leakage calculation?

Normal average residential areas have a predictable usage pattern.

Industrial areas will differ

Specific commercial activity such as farming or garden centers will have seasonal changes to usage patterns

Areas with different demographics of people will show different usage patterns

Important to note this as to not cause a false suspicion of leakage.

What is the purpose of a DMA?

• Splits the network into discrete metered areas using boundary valves

• Used to monitor leakage and consumption per area

• Makes bottom-up leakage possible

• Makes leakage and usage data more handleable and location specific

• Enables taylored pressure management, reducing leakage, MNF losses, strain on network etc

• Typically less than 1000 props