The regulator has been increasingly critical of the robustness of data used by water companies to calculate supply pipe leakage.

Companies have a statutory obligation to supply reliable and accurate information, and failure to do so is a criminal offence. Despite this, accurate information on

supply and demand, including actual measurements of individual supply pipe leakage and per capita consumption (PCC), is not always available.

Ofwat may now, therefore, challenge data submitted and reject submissions from companies with inconsistent or unsupported information.

Many water companies already employ complex strategies including the assessment of night-time water use in specific districts to derive PCC and assess leakage.

Now for the first time a complementary addition to existing strategies, including those recommended by UKWIR, is available to enable water companies to support the validity of their nightline figures.

The core of this is the Severn Trent Services (STS) Smart Meter. This, with its integral supply pipe leakage detection capability, provides detailed and accurate measurements to strengthen data collected using established methodologies, the company says. And it can stand alone or be scaled up to support a company’s own models.

STS works closely with the utility to establish an agreed deployment of the Smart Meters. This is planned to be representative of a water company’s connections to their existing range of properties and provide results in relation to the area profile.

Once installed, the meters are left to monitor consumption for an agreed period. This enables the collection of information on daily consumption, including supply pipe leakage. The data collected is then analysed and a report produced. This analysis complements and

validates a company’s existing strategies, such as data derived using UKWIR guidelines, enabling a report to be provided to the regulator.

The resulting fully validated report forms a defensible part of the utility’s Ofwat report. And it can be used both as independent data or to verify the company’s own overall model. Typically, a report can be delivered within six weeks from meter installation.

Pipe repair

After the initial submission to the regulator, the system continues to monitor at 60-second intervals to provide an elaborated annual report. And data collected can be used to guide a company’s ongoing meter installation programme and provide a better understanding of the economic cost of supply pipe repair.

STS has developed a range of analysis tools that can provide a consumption and leakage profile, including PCC and average daily consumption per property.

Likewise, comprehensive supply pipe leakage data is available including percentage of properties with leaks, volume of individual leaks and proportion of consumption due to leakage. If required, STS relates the data collected to the property profile type to enable the utility to better understand the economic cost of supply pipe repair.

This includes an assessment of leakage volume relative to the predicted cost of repair, complete with cut-off thresholds.

And following repair, STS collects the data again to check the success of the repair and eliminate the possibility of multiple leaks.

Additionally, by correlating the water saved with the actual cost of repair, further thresholds can be established to support the meter installation programme. Using this evidence base, the water company can justify its meter location strategy and select the best property site for installation, by reference to the profile data established.

Commenting on the new strategy, STS business development director Dr Neil Furmidge says: “This is a timely development, which we believe will be welcomed by the industry. Our new approach fully supports the excellent work being undertaken by water companies by verifying existing leakage assessment strategies, such as those recommended by UKWIR, to provide a valuable and defensible part of their Ofwat reporting.”

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