The City of Oslo’s drinking water comes from the nearby lakes of Maridalsvannet (photo) and Elvåga. From here, the City of Oslo uses around 100 million cubic metres of water for the city’s drinking water supply. Photo by: Wilhelm Joys Andersen.

By means of innovation, new technologies and thorough leak detection methods, Greater Copenhagen Utility, HOFOR, has brought water losses in the capital of Denmark down to a minimum and sustainable level. HOFOR has succeeded in reducing specific water losses by more than 75 percent since 1977 where the water losses have been reduced from 13.3 m³/day/km main to 3.1 m³/day/km main corresponding to an overall reduction in NRW level from 9 to 5 percent.

This result is especially remarkable because 50 percent of the water pipes in Copenhagen are laid before 1945, 22 percent are more than 100 years old, and 55 percent of the pipes are cast iron.

HOFOR is one of the world’s leading utilities in reducing leakage. This is thanks to the way they combine multiple technologies and methods, including noise loggers and advanced microphones, meters installed at every customer, hydraulic models, capacity building programnes as well as sectioning of the network into District Metered Area (DMAs), and online water balance monitoring on DMA level.

HOFOR has at present completed the implementations of DMAs in the seven municipalities outside Copenhagen city centre.

Routine area sweeps

First and foremost, in-depth knowledge on system conditions is vital. For instance, HOFOR reviews the entire pipeline network of the capital every third year. Leaks are identified by listening for leak noise at selected valves at strategic locations using advanced sound detecting equipment.

Furthermore, applying condition assessments from scheduled maintenance is an important part of the renovation strategy. This way Greater Copenhagen Utility is able to initiate repairs in time to prevent failure and thereby avoid massive water losses. This is especially crucial in the older areas of the city, as the 100-years old streets are at risk of collapsing if an underground leak is not identified and fixed in time.

HOFOR has installed permanently deployed noise loggers in such high-risk areas of the city as an important part of the active leakage control strategy. The noise loggers automatically deliver data every day to assist in early identification of potential leaks.

A change in leakage management strategy

During the last decade Greater Copenhagen Utility has changed the leakage management strategy from manual scheduled leakage surveys at regular intervals to active leakage control by combining multiple data sources, SCADA, smart metering, hydraulic models and noise loggers. Data from all systems are integrated in the online management information system, HOMIS. By integrating data from different systems, the utility is able to identify and target the weakest areas and pipeline segments, as well as quickly and automatically locate leaks and prioritise which leaks to be repaired first. This change in strategy optimises both operations, maintenance and the human resource management.

The LEAKman partnership continues to support the reduction of water losses in the Danish water sector through research projects where the partnership formed under LEAKman is a key in the development of competences and talents.

To date the partnership has engaged and facilitated one PhD and several MSc projects working with data and cases delivered by the utilities and supervised by NIRAS and The Technical University of Denmark (DTU). The candidates have contributed with valuable results and expertise in data and leakage management of water distribution systems, which in turn has been communicated through academic journals and conferences.
Data from the LEAKman partnership will continue to provide the basis for research and advanced developments within several areas including water loss control, demand forecasting, hydraulic modelling, and water quality monitoring.

Rosa Marie Mathiasen, engineer at NIRAS, has already been testing the tool on a sample of approximately 100 meters in Malaysia and 800 meters in Oslo.

Experiences from Malaysia and Oslo demonstrate how useful a new online tool, the meter data validation tool, is. The tool determines if deviations in data from water meters indicate an actual water supply issue or if the meter simply needs a calibration.

Measurements spanning twenty-six hours a day, several different values with the same time stamp and right out flatlines are some of the dubious measurements which indicate that a water meter should be calibrated or replaced.

From Jonas Kirstein’s PhD thesis – read it here.

Jonas Kirstein, PhD from DTU in collaboration with NIRAS, devoted a large part of his study to analyse the most common mistakes found in the data from meters installed throughout water distribution networks. During his research, based on 32 months of monitoring data of three Danish utilities, Jonas discovered that up to 35% of the meter data is dubious.

Data testing and validation

Many utilities depend on the collected data from water distribution networks, among other things, to detect leakages, to run hydraulic model simulations or to apply machine learning approaches on the collected data. However, all these approaches depend on data that represents the actual state of the network and not on data that contains too many erroneous measurements.

If the data input is erroneous, the results of data-dependent applications may lead to wrong conclusions. Thus, to avoid misinterpretation of data, Jonas has developed a tool, the meter data testing tool, that identifies when dubious measurements are received from a meter. The tool only takes a few seconds to analyse most of the data for any individual meter. This means, that utilities can react quickly to actual water loss issues and dispose their resources tactically in case of a meter error.

It is not much of a stretch to imagine how valuable this tool can be in detecting problems in the meters, especially in countries where meter data is less reliable than the Danish data.

In the field

The tool has already been tested on a sample of approximately 100 meters in Malaysia and 800 meters in Oslo. Data validation of the 100 Malaysian meters showed that many meters were sending poor data, or no data at all.

“It turned out that many meters were not properly installed, causing the meters to report erroneous data,” says Rosa Marie Mathiasen, engineer at NIRAS, Denmark, and responsible for testing the tool.

The tool has been used as a part of a model calibration:

“100 meters are considered a small batch taking the model area into consideration,” Rosa says, “but that only amplifies the need for correct data, since this is the only data we can collect in this area.”

Due to the results of the meter data validation tool, the Malaysian utility company is currently working on resetting the meters that were not installed properly.

Currently, Rosa is analysing the results of the 800 Oslo meters. She can run the analysis on her computer anywhere in the world:

“The tool is online, so I can just set my computer to start analysing. The advantage of the tool is that we can provide an overview of the meter errors to the utility company, which makes it easier for them to prioritise which meters to look into first, something that can be challenging otherwise,” says Rosa. She looks forward to using the tool again, once the meters are calibrated: “It will be exciting to see how the new data compares to the first measurements.”

Great potential

The meter data validator has great potential, Klavs Høgh, Project Director at NIRAS, says. He has been closely involved in developing the tool as one of the supervisors during Jonas’ PhD.

“We see that utilities are becoming more and more data-driven. For example, advanced applications for improved water loss control rely heavily on the collected data. It is therefore very valuable to use accurate data, so that decisions are based on realistic scenarios and not faulty data.”

Even though the tool shows individual meter data, it is possible to compare data from all meters in a geographical area. This means that temporary anomalies can be corrected based on the data from the surrounding meters.

Klavs elaborates: “If a meter suddenly stops sending data, but the surrounding meters keep sending, this probably means that something blocks the signal, like a parked car.” In this case the utility company won’t waste resources sending an employee to the spot. Only if the meter remains flat for a longer period than feasible, utilities should act.

Besides improving the data on which strategical decision are made by utility companies, the tool also reduces costs for monitoring and maintaining the network.

“We are moving towards smart water solutions, where all individual measurements are part of a bigger network. This means that utilities in the future can swap their calendar driven maintenance schemes with data driven schemes, where they can repair if the actual need is there, not because the calendar says so.”

The tool is now accessible online for all utilities and those with access to meter data to test. Please contact Jonas Kirstein (JKI@NIRAS.DK) if you have questions regarding the meter data validation tool.

The water supply plant at Via Bassa, San Giovanni in Persiceto, is managed by Gruppo HERA and feeds two aqueduct branches, serving two different parts of the city, including a high water demand hospital. The existing pumping system was made by four end-suction Grundfos pumps controlled to guarantee a discharge pressure of 2.6 bar.

HERA is focused on innovation and new solutions and has a strong partnership with Grundfos not only for new pumps, but also for the design and deployment of tailormade control systems and solutions in the water networks applications.

HERA‘s target in San Giovanni in Persiceto was to stabilise water network pressure and to supply the right pressure 24/7 at the critical points.

The solution

To reach their targets HERA initiated a pump upgrade project handled by Grundfos including several steps; audit on the existing pumping system, pressure monitoring at the network’s critical points, data analysis and reporting to obtain a clear picture of the network and to reveal the potential benefits of different solutions for pressure management.

HERA proceeded as suggested by Grundfos by upgrading to a new and more efficient pumping system and by introducing Demand Driven Distribution (DDD) control logic. Demand Driven Distribution (DDD) is a solution patented by Grundfos for intelligent management of pumping systems, capable of adapting to the actual requirements and service level of the water networks.

The results

Thanks to the DDD control, HERA has been able to stabilise and reduce the pressure at the most critical points guaranteeing a higher comfort to the customers and a lower stress to the entire supply area resulting in reduction of water losses, water hammer and pipe bursts.

Numbers to highlight, due to the DDD control and upgraded pumping system:

• 2.3 bar at the critical points (instead of previous 2.7 – 3 bar)
• 110,000 kWh/year estimated energy saving
• 58,000 m³ of water loss avoided
• 36 t of CO2 saved
• 0.09 kWh/m³ specific energy (instead of previous 0.13 kWh/m³)
• 1 year and 5 months of payback time

Courtesy: Grundfos and Gruppo HERA

The City of Oslo’s drinking water comes from the nearby lakes of Maridalsvannet (photo) and Elvåga. From here, the City of Oslo uses around 100 million cubic metres of water for the city’s drinking water supply. Photo by: Wilhelm Joys Andersen.

Historically, Norway has had almost unlimited access to drinking water at quite low costs. As a result, there has only been little focus on NRW and NRW-levels around 50 percent were not unusual.

Over the past 5-10 years, though, this has changed as high NRW also leads to high maintenance and production costs as well as overcapacity. The city of Oslo is growing and urgently needs to secure a sustainable drinking water supply for the future. In 2018 around 35 percent of drinking water was lost in the network on its way to the customer. To bring down this level of water losses several initiatives have been taken, and the utility, Oslo Vann, launched a Non-Revenue Water (NRW) master plan targeting to reduce NRW to 20 percent by 2030.

Real-time hydraulic overview to prioritise efforts

The plan includes the implementation of Aquis, an online hydraulic modelling system, and HOMIS, an online Holistic Management Information System. With the support of these two tools, Oslo Vann has established a real-time hydraulic overview of their 1,550 kilometres of main pipeline network, divided into 7 regions, 43 pressure management areas and 69 District Metered Areas (DMAs).

The Aquis model provides real-time hydraulic simulations where selected results are connected to HOMIS, and combined with other data from CIS (Customer Information System), GIS (Geographical Information System) and SCADA (Supervisory Control And Data Acquisition) to automatically calculate and maintain a set of Performance Indicators monitoring the performance on DMA level. This overview is used to identify problematic areas and prioritise leakage management activities. The leakage management system is dynamic, and designed with open interfaces allowing new technologies to be added to improve the utility’s NRW management. Oslo Vann is already planning to add pressure management, noise loggers, and smart meters.

Innovation and new developments

Another aspect of major importance for the utility to reach their NRW reduction target, is the introduction of a capacity building program targeted for operators and engineers, which provides the participants with a variety of knowledge and tools for improved NRW management and water loss control from monitoring and prioritisation to leak detection and repair.

Courtesy: NIRAS and Municipality of Oslo

The pumping station is equipped with five intelligent pumps from Grundfos.

In Copenhagen, Denmark, the local utility company Frederiksberg Forsyning has invested in intelligent pumps and advanced pump control with Grundfos DDD – Demand Driven Distribution – to reduce water leakage and energy consumption.

A state-of-the-art pumping station has been established by the utility company Frederiksberg Forsyning in the capital of Denmark. Consequently, two District Metered Areas (DMA) in the Copenhagen urban district Frederiksberg will now be supplied with drinking water controlled with Grundfos DDD – Demand Driven Distribution utilising advanced technology and internet of things (IoT).

Using hydraulic modelling the system is designed to ensure the required pressure at all customers. The purpose of the new ‘pressure control station’ is to provide local pressure optimisation in the two DMAs supplied directly from the pumping station. The pumping station is equipped with five intelligent pumps from Grundfos with each a capacity of 45 cubic meters of water per hour (45 m3/h).

Watch the video

Demand Driven Distribution

The pumps operate and are controlled with Grundfos DDD – Demand Driven Distribution. This means that, pressure in the supply area is continuously adjusted to meet the demand at all times – including any emergency needs for fire flow. As a result, the pressure does not drop when demand is high. E.g. the pressure is optimised to meet the demand in the morning, where many households use water for baths and morning routines.

When adjusting the pressure to the current demand, the utility company can optimise the average pressure and avoid operating with a constant high pressure. Intelligent pressure management ensures many advantages for the local utility company:

1. Less stress on the network due to stable, optimised pressure
2. Less water lost at burst and through minor leaks, that inevitably exist in all water supply networks
3. Fewer new leaks occur
4. Reduced energy consumption through improved energy efficiency
5. Reduced operation and maintenance costs

In order to implement Demand Driven Distribution a series of network pressure sensors has been installed in the two District Metered Areas. The Demand Driven Distribution controller has been connected to the network pressure sensors. This allows for control of the pumps in accordance with data logged on a daily basis using an adaptive control algorithm. The measured data are then used for adaptive control of the pumping station which enables the pumps to supply the required pressure according to the demand at all times.

Part of the LEAKman project

The new approach to local pressure optimisation with Grundfos DDD is implemented in two of the 20 District Metered Areas in Frederiksberg Forsyning. In these two areas there are a potential to operate at a lower water pressure when the actual demand is low. As a result, the pressure is continuously optimized in the network whilst ensuring a more stable, and minimum required pressure at all customers.

This implementation of Grundfos DDD is a part of the LEAKman project – a partnership initiated to demonstrate Danish solutions for limiting drinking water loss and pave the way for new technology. Read more about the nine partner companies here.

In this case, the LEAKman partner Grundfos provided five of their highly energy efficient pumps. The consulting engineer NIRAS – also a LEAKman partner – contributed with knowledge, hydraulic modelling in the design phase and when constructing the pumping station building.

Credit: Hans Søndergaard – A look into one of the three monitoring chambers in Klampenborg. A Novafos staff member is inspecting the newly installed smart valve.

The DMA in Klampenborg, north of the Danish capital Copenhagen, is located along the coastline of the Oresund strait and is located in a low-lying area. Consequently, the pressure in the water mains is high as the water supply comes from sources located inland at a higher elevation.

Most (almost all) water supply networks are prone to leaks. Some are big and will typically be detected by the utility company staff or reported by customers. Some are minor and will never be spotted or repaired during the entire lifespan of the pipes. The difference in altitude and pressure means, that the DMA in Klampenborg will lose more water through leaks, compared to other areas situated at a higher altitude.

Therefore, advanced pressure control valves have been installed at two of the three inlets to the DMA. They optimise and stabilise the pressure and ensures that the setpoint is at a minimum. At the third entrance, a control valve has been installed and configured as a pressure sustaining control. The valve is closed during normal supply conditions, and automatically opens in case of unexpected pressure drops or emergencies.

Data from the flow meters in the DMA inlet enables the utility company to compare flow data with consumption data received from the customer smart meters. Thereby the utility can monitor the flow balance on a daily basis and thus calculate water losses at DMA level and thereby reduce the leak run times significantly.

With the new valves and knowledge about the operational and hydraulic behaviour of the DMA, the utility company has successfully reduced average pressure by 29 pct (from 46.7 mwc to 33.3 mwc). As a result, water is saved, as corresponding decreases in leakage level and burst frequencies are expected.

Watch the video

The City of Oslo’s drinking water comes from the nearby lakes of Maridalsvannet (photo) and Elvåga. From here, the City of Oslo uses around 100 million cubic metres of water for the city’s drinking water supply. Photo by: Wilhelm Joys Andersen.

In 2019, the town of Oneida, Tennessee was experiencing an impossible situation. With increasing state regulations and massive water loss, the water department was taken over by the local government.

Oneida produces 1,500 million liters of water a year and saw a 51% total water loss, meaning that over 750 million liters a year were being lost, mainly to leaks. The loss cost the city $186,000 annually and caused the water treatment plant to operate on 12- to 14-hour days to keep up with demand.

Oneida faces a complex set of conditions to provide quality water on tap. The diverse and rugged topography creates an obstacle course for water distribution and maintenance. The water system consists of one water treatment plant feeding two water supply reservoirs which again supplies the customers with drinking water through an aging water distribution system. Routine droughts are also impacting the water supply.

They installed 4,600 Kamstrup meters with built-in acoustic leak detection and erected 12 collectors within five weeks. During the initial three-month period after the Kamstrup meters were installed, Oneida uncovered and repaired a single leak that had been running for five months at an estimated cost of $21,000 per year and Oneida’s water loss was reduced by 23%.

Overall, the city’s 51% total water loss was reduced to 38%, and the water treatment plant operation was reduced by three hours per day. With leak detection on its side, they have transitioned to recovery and are steadily upgrading their infrastructure, utilizing a two-man crew to fix an average of five to six leaks per day.

The water department is methodically addressing leaks and repairing their infrastructure. The city aims to repair two miles of pipe per year and reduce their water loss to under 15%. With leaks and loss under control, the Oneida water treatment plant continues to improve its operating time and Oneida is now a showcase for municipal water management in Tennessee.