Old City of Jerusalem presents challenges for leak detection

Each TaKaDu customer has a story – varied types of service areas, different regulatory environments, and specific challenges. One of which is the story of Hagihon, the water and wastewater utility for the Jerusalem area of Israel.

Each day, Hagihon provides more than 220,000 cubic meters of drinking water, through a total pipeline length of 1,300km that runs throughout Jerusalem and surrounding areas. The utility serves around a million people, about 10% of the Israel’s population.

The Old City is a small part of Hagihon’s service area, but it is the most complex. A 0.9km2 walled area in the middle of the moder city, it is home to some 40,000 residents, and is very crowded with houses and other buildings built around narrow alleys.

Water is delivered to the Old City through pipelines that pass through four of the nine open entrance gates in the Old City wall. These are also the entrances to the four district metered areas (DMAs) that the Old City is divided into. A fifth pipeline has been laid through another gateway and will be metered soon.

Map of Jerusalem, the Old City is on the right; its borders are marked in grey.

Complex leak detection and repair
Most of the pipeline under the Old City was laid during the 1970s, and is made either galvanised iron or steel. The water loss in the Old City DMAs ranges from 9.5-19% depending on the DMA.

The Old City of Jerusalem was conquered, destroyed, and rebuilt many times in its history, creating soil made of layers of ruins built up over the course of 3,000 years. As a result, water from leaks infiltrates through the layers for a very long time, and across a long distance, before it reaches the surface. This means that leaks can last a very long time before they are detected, and is difficult to locate the source.

For Hagihon, the biggest threat is not non-revenue-water, but rather that an ongoing leak could seriously damage old buildings, which have no iron foundations, or worse, cause them to collapse.

But, using fixed acoustic meters to detect the location of the leak is possible only on a very small scale, as there is strong resistance from residents, who do not like seeing suspicious equipment within the walls of the Old City – there are many politically and religiously sensitive issues.

Even once leaks have been discovered, repairing them can be very difficult. Due to the density of the Old City, and the small alleys, it is impossible to bring in heavy machinery. All repairs must be done manually.

Hagihon faces many other operational complexities in the Old City. For example, if a new pipeline needs to be constructed to replace an old one, the utility must first place a temporary line aboveground because there is simply no space to put a new permanent pipe next to the old one. Only then can Hagihon remove the old pipeline and install a new one.

With the many historical and religiously important sites in the Old City, Hagihon must act with extra sensitivity when construction, maintenance or repair work is needed. In addition to obtaining permission from the police and city council, Hagihon must also get authorisation from many other organisations before moving even a single stone in the Old City – among them, the Israel Antiquities Authority, the East Jerusalem Development Company, and the Committee for the Preservation of Gravesites.

Due to these challenges, leaks typically run for a long time before they are fixed and faulty connections are replaced less frequently. As a result, the water network within the Old City is older than in the rest of the city.

A chance event uncovers a major leak
A case study to demonstrate some of the challenges Hagihon faces is a leak event from April 2018.

Over the previous few months, Hagihon’s water loss engineer and the TaKaDu software had both identified an increase in water loss, but had no way to determine the exact source. Then, water that penetrated the floor of one of the houses in the Muslim quarter was reported by the homeowners, initiating a suspected-leak event in the area close to the Damascus Gate in the Old City walls.

With no acoustic loggers in the area, and all the other challenges noted above, it was impossible to properly investigate to locate the source of the leak, and it could have continued for a long time.

But soon after, a police jeep driving in the area accidently broke a paving stone, and by chance that small accident revealed the location of the leak. A team from the water loss contractor that happened to be scanning the area arrived and began marking and repairing the leak.

Based on TaKaDu monitoring, Hagihon estimated that about 2,325m3 of water was lost due to the leak.

Early leak detection helps customer
Elsewhere is Jerusalem, where the water utility can use modern equipment and processes, the TaKaDu system is able to do far more than identify the existence and extent of a leak. For example, in one case, the system alerted Hagihon about a sudden flow increase event that began on the evening of September 8. The water loss was measured at about 11m3/hr. Hagihon was able to quickly find the source of the leak in one of the service pipes and fixed it within the next few days. The total estimated water that was lost was about 600m3.

The early detection saved a lot of money for the customer, a large consumer, that, had not been detected so quickly, would have ended up paying for far more water than it actually consumed.