Customer pipes responsible for a third of leaks

In July 1998, Anglian Water was set one of the toughest leakage reduction targets in the industry.

This represents a reduction of some 13% of total losses, to be achieved within a period of just 8 months.

Although estimates of total leakage are progressively becoming more robust, the CSPL component remains largely unknown. Little or no industry research has previously been undertaken.

This is because until the Water Summit in July 1997, CSPL was the sole responsibility of the customers.

Following the summit, companies agreed to assume responsibility for leakage from the customers assets and accepted that leakage targets will be set which include reductions of CSPL.

50 of the companies 425 distribution ones (DZs) were selected by Anglian for this purpose and scheduled for completion within year one.

Achievement of the targets for some companies, especially for those with low levels of leakage such as Anglian Water, depended upon achieving large reductions in CSPL.

This is because higher leakage values could be attributed to excessive CSPL.

Moreover, for Anglian, this was especially onerous because the target was very tough and the new levels of leakage required have never been achieved before.

Anglian responded to this challenge by implementing an extensive leakage reduction programme covering all components of leakage.

One of those initiatives is the CSPL project which is targeted specifically at our customers’ own pipes.

A coordinated campaign involving a customer awareness literature drop at the local level and a dedicated free phone contact line ensured customers are fully supportive of the initiative.

A ring-fenced capital scheme costing £5.8M over a two year programme was designed and implemented by Anglian, with principal objectives summarised as follows:

• Assess the level of customer’s leakage using available existing data and new data
• Identify the optimum economic level of CSPL
• Contribute to the overall leakage reduction target
• Develop a sound strategy for managing CSPL
• Produce a methodology for implementing the strategy and meeting targets.

A structured approach is needed to achieve these objectives. Pilot areas are selected based on assessments of total leakage being above an acceptable level.

The structured methodology outlined below was designed to provide the data needed to deliver the project objectives:

1/ Assess the level of leakage by monitoring minimum night flow

2/ Carry out leak detection on the distribution mains

3/ Carry out repairs whilst minimum night flow is being monitored

4/ Carry out leak detection on stop taps to identify leaks on communication pipes and customers’ pipes

5/ Repeat step 3

6/ Assess the benefit of repair by review of change in night flows

7/ Ensure that detection and repair costs are monitored.

Methods for collecting the data for the leakage detection, repair, cost and night flows were established. A proprietary database was produced to store and analyse the collected data.

The outcome of year one of this project contributed significantly to the overall reduction in leakage.

This reduction is now estimated at 25 Ml/d, out of a total achieved reduction by Anglian of 34 Ml/d.

7765 leaks were found during the year 1998/9. The majority of these were located in the 50 highest leaking DZs.

One such success story is the leakage reduction programme in the cathedral city of Lincoln. This busy city is situated in the northern part of Anglian’s area. The population is around 100,000.

The city is made up of a considerable number of terraced properties dating back to the early part of the century and several large industrial consumers.

The pipe work is predominantly cast iron, with lead and copper being the main materials used for supply pipes.

For a period of 12 months from July 1997, an average of 7 detection technicians and 3 repair technicians were dedicated to the Lincoln city DZ.

A total of 490 leaks were found and repaired. It is worth noting that 26% of the leaks were from customer owned supply pipes, 3% from internal plumbing and 39% from stop taps.

Following repairs, night flow for the Lincoln DZ have dropped dramatically, indicating that a significant reduction in leakage has been achieved.

The reduction has been estimated at around 3.8 Ml/d. The timing of the leakage reduction is consistent with the repairs.

Significantly fewer leaks were detected in the latter stages of the programme, suggesting that nearly all of the leaks had been detected.

Two detection technicians are now charged with ensuring that the low levels of leakage in Lincoln are maintained.