First-fix repair scheme to stem 35m litres of water leaks daily
05 May 2015
Author: Jerry Grant, chartered engineer and Engineers Ireland fellow, head of asset management, Irish Water
Irish Water has targeted reductions in water losses as a key priority in delivering better and more cost-effective water supply service to customers. One of the common methods employed by water utility companies internationally to address water losses through leakage is to provide customer support to address leakage within the boundary of the private property known as customer side leakage (CSL).
Leakage from the water networks averages over 49% across the country – twice the level of that in the UK, where the assets are comparable but have been more intensively managed over the last 20 years and several times the typical figures in Germany, Denmark and the Netherlands.
Historically, utility companies have struggled to quantify where in their networks water losses were occurring. The scale and geographic penetration of the Irish Water metering programme presents a unique opportunity to understand the flow of water through the network in Ireland, and to gain an accurate understanding of the proportion of water that is being lost through customer side leakage.
The meters selected by Irish Water feature automated meter reading (AMR) technology. During the meter-reading process, data is captured remotely that will inform Irish Water if the meter indicates a leak or continuous flow at the property. A continuous flow of 6 litres per hour through the meter over a 48-hour period will trigger a constant flow alarm (CFA). It would be extremely difficult to identify any leak on a supply pipe occurring at a continuous flow of 6 litres per hour without carrying out significant excavation works. At the end of March 2015, Irish Water had read almost 520,000 meters – of these, some 37,033 or 7% of meters installed had recorded a CFA. Figure 1 shows the number of CFAs by average daily usage.
Table 1 presents the regional breakdown of constant flow alarms by average daily usage and Figure 2 shows a map of the metering regions.
|Region||>10m3/ day||5-10 m3/ day||4-5 m3/ day||3-4 m3/day||2-3 m3/day||1-2 m3/day||0.5-1 m3/day||< 0. 5m3/day|
Table 1: Number of Constant Flow Alerts by Usage by Region
The volume of water wasted due to the customer side leaks over 5m3/day is significant, at almost 35 million litres of treated water a day. This is enough water to meet the daily water demand of over 115,000 homes. Based on the data collected, we estimate that over 31% of the water provided to domestic customers is lost through leakage on customer properties.
‘First fix’ scheme
In May 2014, the Government committed to introducing a ‘first fix’ scheme, which will assist customers who have had a meter fitted with the repair of external leaks located on their private supply pipe. Irish Water has submitted its First Fix Policy to the Commission for Energy Regulation. This is currently the subject of a public consultation until the 14 May 2015. This is the first initiative to address CSL in Ireland. In comparison, UK utilities have had policies to support customers in addressing leaks on their private supply pipes for many years.
Under the Water Services Act, homeowners are responsible for the maintenance and repair of all pipework in their home and on their property and this responsibility has not changed. Irish Water’s interim First Fix Scheme will support customers in reducing the water wasted through leaks on their property. The Interim First Fix scheme is available to customers who have registered with Irish Water and had a domestic meter installed. Figure 4 shows the stages for customer notification, leak investigation and repair under the Interim First Fix Scheme.
The development of the interim First Fix Scheme and Irish Water’s proposed continuing First Fix Scheme is based on a pilot study (August-December 2014) of 532 metered properties in the North Kildare and North Dublin City areas with an active constant flow alarm. The metering programme commenced in Kildare so these meters had the longest time in service and provided a good source of data. Dublin city was selected as it has a wide range of property type and pipe ages and materials.
This provided real data and scenarios to understand the complexities of customer side leakage and to determine whether the policy provided adequately for the range of potential customer situations. The experience and learning gathered during this trial provided a basis to inform the process and system design, model deployment scenarios and support the implementation of an enduring solution.
A notification letter was issued to each of these properties and customers were requested to contact Irish Water. Overall between field visits and mail notifications 82% of customers contacted engaged in the process providing a sample of 436 properties. Of the leak investigations completed, some 44% in Kildare resulted in a qualifying leak being identified. In Dublin, this conversion rate was significantly higher with 58.5% resulting in a qualifying repair. The higher conversion rate in Dublin may be associated with older supply pipes.
This study also found that internal plumbing issues were a significant contributor to the water lost at these properties; over half of the leaks detected were due to internal plumbing issues, with faulty toilet cisterns giving rise to 40% of these. Table 2 below provides a breakdown of the non-qualifying leaks by category. The volume of internal plumbing issues resulting in wastage was not anticipated and this is a significant finding from this trial. It was noted that a number of houses in some new developments had common internal plumbing issues e.g. running toilet cisterns. Internal supply pipes leaks were for the best part traced back to home-upgrade works e.g. renovations, extensions, conversions etc.
|Non-Qualifying Leak Category||Dublin City||Kildare||Total|
|Internal – Leaking Cistern||29.8%||47.7%||42.2%|
|Internal – Other (e.g. under floor, beyond Internal Stop Valve)||52.6%||35.2%||40.5%|
|Internal – Leaking Storage Tank||5.3%||10.2%||8.6%|
|Internal – No Internal Stop Valve||7.0%||0.8%||2.7%|
|External – Wastage||1.8%||2.3%||2.2%|
|Heavy Consumption Only||0.0%||1.6%||1.1%|
|Internal – Wastage||0.0%||0.8%||0.5%|
The volume of water attributable to properties with non-qualifying leaks is substantial at 500m3 per day if these properties are returned to an estimated ‘normal’ average consumption of 300l/day.
Irish Water leaks – pilot scheme
A total of 147 repairs were completed as part of this pilot scheme through a combination of local repairs and service replacements. The savings related to these repairs are in the region of 800m3 per day. Local repairs were typically carried out where upon excavation the pipework appeared to be in good condition, but a fitting or join had failed.
Full service replacement was typically used on older metal pipes e.g. copper and lead, as these are more likely to have damage and wear and tear. This was largely achieved using a mole plough to install a new pipe by trenchless technology. This is a less intrusive option and minimises the amount of damage to surfaces and re-instatement required. Common causes of failure can exist in estates, which can simplify the investigation and repair process. In one particular modern development, a total of 15 leaks were identified out of 213 metered properties. All of these related to poor quality/incorrect brass fittings being used at the point of entry, which had failed.
To date, Irish Water has issued almost 3,000 notifications as part of the Interim First Fix Scheme and carried out over 250 leak repairs and almost 500 leak investigations. Subject to approval from the Commission for Energy Regulation and acceptance of the draft continuing First Fix Scheme, we anticipate that we will issue in the region of 70,000 notifications to homeowners with a CFA.
This will be done on a prioritised basis of the largest leaks first in order to achieve the greatest water savings. We anticipate that up until the end of 2016, we will undertake approximately 50,000 leak investigations and 25,000 leak repairs.http://www.engineersjournal.ie/2015/05/05/irish-water-leaks/http://www.engineersjournal.ie/wp-content/uploads/2015/04/Jerry-Grant-Irish-Water-1024x682.jpghttp://www.engineersjournal.ie/wp-content/uploads/2015/04/Jerry-Grant-Irish-Water-300x300.jpgCivilDublin,infrastructure,Irish Water,Kildare