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Buildings and Cities

Water Distribution

Pumping water from source to treatment plant to storage and distribution requires enormous amounts of energy. Utilities use the phrase “non-revenue water” to describe the gap between what goes into a municipal water system and what ultimately comes out the tap. The World Bank calculates that 8.6 trillion gallons are lost each year through leaks, split roughly in half between high- and low-income countries.

Producing billions of kilowatt-hours of electricity to pump water through breaks in the world’s water-distribution networks—rather than into homes or businesses—is expensive. It also produces unnecessary emissions. By minimizing leaks and losses, both energy and water are saved.

Improving the efficiency of water distribution largely depends on management practices. The torrential bursts that cut off service and submerge streets are not actually the worst from a waste perspective: They demand attention and immediate remediation. The bigger problem is with smaller, long-running leaks that are less detectable. Vigilant, thorough detection and speed to resolution are key.

Addressing leaks requires financial investment, but doing so is the cheapest way to source new supply and serve growing urban populations. Those same practices make municipal water systems more resilient to water shortages.

References

Pumping [water]…enormous amounts of energy: Pabi, S., A. Amarnath, R. Goldstein, and L, Reekie. Electricity Use and Management in the Municipal Water Supply and Wastewater Industries. Palo Alto: Electric Power Research Institute, 2013.

8.6 trillion gallons…lost [to] leaks: Kingdom, Bill, Roland Liemberger, and Philippe Marin. The Challenge of Reducing Non-Revenue Water (NRW) in Developing Countries. How the Private Sector Can Help: A Look at Performance-Based Service Contracting. Washington, D.C.: The World Bank, 2006.

“steady, moderately low level of pressure”: Bornstein, David. “The Art of Water Recovery.” New York Times. July 10, 2014.

Britain…National Leakage Initiative: Bornstein, “Recovery.” 

United States…one-sixth of distributed water escapes: Thornton, Julian, George Kunkel, and Reinhard Sturm. Water Loss Control. New York: McGraw-Hill, 2008.

low-income regions…50 percent of total volume: Farley, M., G. Wyeth, Z.B. Ghazali, A. Istandar, and S. Singh. The Manager’s Non-Revenue Water Handbook: A Guide to Understanding Water Loss. Bangkok, Thailand: Ranhill Utilities Berhad and the United States Agency for International Development, 2008.

[if] halved…supply some 90 million people: Kingdom, Bill, Gerard Soppe, and Jemima Sy. “What Is Non-Revenue Water? How Can We Reduce It for Better Service?” The Water Blog. The World Bank. August 31, 2016.

Manila…[successes of] water utility: Bornstein, “Recovery”; International Water Association. “The 2013 IWA Project Innovation Awards—Development” Press release. September 2013.

World Bank–International Water Association partnership: World Bank. “The World Bank and the International Water Association to Establish a Partnership to Reduce Water Losses.” Press release. Stockholm, September 1, 2016.

view all book references

Technical Summary

Water Distribution

Project Drawdown defines water distribution as: reducing water leakage or oversupply of regional water, which reduces pumping and pressurization electricity and associated greenhouse gas emissions. This solution replaces conventional water system management with no specific leak detection program.

Water utilities are among the biggest consumers of electricity globally, corresponding to about 1% of total electricity use in the world. Up to 80 percent of that energy is used for pumping alone. However, a significant amount of water is lost in the distribution network (e.g. by pipe leakage, meter error, and unauthorized consumption): the global average loss is estimated at 35 percent. This has a direct impact on the production cost of water, as well as on the available quantity of potable water. Saving just half of these losses would supply water to an additional 100 million people (The World Bank, 2006).

There are a number of ways to minimize leakage. Pressure management and active leak detection are two major ones. Pressure management involves installing pressure valves at water inlets and outlets to better monitor the flow of water and pressures, and leads to reductions in pipe bursts and leaks from broken pipes. Active leak detection can be performed using a range of technologies, such as thermal imaging, noise logging, or gas injection. Prices and precision vary for these approaches, but the value can be high, especially for high operating cost, high water scarcity regions.

This analysis examines the financial and emissions impacts of a high adoption of pressure management and active leak control globally, and compares that to conventional system management with no specific leak detection program.

Methodology

Total Addressable Market [1]

Project Drawdown’s method starts by estimating how much water is actually used globally by municipalities. This was done in two ways. An exponential curve of water use per year was developed from 20 previous estimates of global water distribution for specific years dating from 1900 to 2025 (Hejazi et al, 2013). This estimate was combined with empirical data reported by hundreds of water utilities in the International Benchmark Network Database (IB-NET, n.d.) to arrive at estimates for per-capita water production for all regions in the world. Combined with water supply statistics from the World Health Organization and United Nations Children's Fund (WHO/UNICEF, 2015) to arrive at Urban and Rural shares, the total addressable market for each region was obtained. Relying on both recently reported data and theoretical estimates over several years and studies strengthened the final estimate used: 502 billion cubic meters of water treated and supplied in 2014.

Adoption Scenarios [2]

Impacts of increased adoption of water distribution from 2020-2050 were generated based on three growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels.

  • Plausible Scenario: The adoption of pressure management and active leak control is assumed to rise linearly to 80 percent of the global water distribution network.
  • Drawdown Scenario: This linear growth reaches 85 percent of the global water distribution network.
  • Optimum Scenario: In the most aggressive adoption scenario, the linear growth reaches 95 percent of the global water distribution network.

Emissions Model

Emissions estimates were calculated for electricity consumption for water treatment and distribution (with a weighted share for each of desalination, surface water, and ground water). The result was 1.27 gigawatt-hours of electricity per million cubic meters of water supplied. Leakage activities were estimated (over 18 data points) to reduce this by 29%, and emissions factors for this grid electricity came from the guides of the Intergovernmental Panel on Climate Change (IPCC).

Financial Model

First costs for pressure management and active leak control were averaged based on how much water they save on average, so are reported here in million cubic meters of water saved. From 9 data points covering Europe, North America, and Asia, the installation cost is US$634,000 per million cubic meters of water saved. [3] No costs were applied to the conventional approach since the solution was assumed to be in addition to conventional techniques. Operating costs for conventional systems were obtained from 5 data points coming mainly from the IB-NET Database and averaging US$444,000 per million cubic meters of water supplied. Data from Kanakoudis & Gonelas (2016) indicates the operating savings coming from leakage reduction activities; this results in a net operating cost of US$211,000 per million cubic meters of water supplied.

Results

Based on the results from Project Drawdown’s Plausible Scenario, reducing non-revenue water would yield a 0.87-gigaton reduction in global carbon dioxide-equivalent emissions from 2020-2050. This is expected to drawdown greenhouse gases in the atmosphere by 0.07 parts per million by 2050, and bring operations savings of US$903 billion. The net cost would be US$137 billion. In the Drawdown Scenario, the emissions impact is 1.1 gigatons, while the Optimum Scenario shows 1.7 gigatons reduced.

Discussion

Since water, energy, and climate change are intricately related, the sustainable water management practice of pressure management and active leakage control would contribute to a strategy of reversing emissions. Though pressure management in water distribution networks is an important and cost-effective initial step in curbing water losses, it is important to note that pressure management is not the complete solution to reducing real water losses, as it does not repair leaks but reduces leak rates and pipe bursts. Utilities, therefore, would need to determine where to deploy pressure management and active leak control, as well as which combinations of these and other solutions are required for managing water losses in their specific situations. Our analysis does not, however, include other leak detection approaches or other water supply systems, such as water conveyance by tanker truck.

Besides the climate change abatement imperative, water scarcity is an equally important concern for which sustainable water management practices are needed at a global scale. There already exists a scarcity of unpolluted water in many regions of the world, and regions with large amounts of water are not guaranteed infinite water resources. Reducing water losses has other manifold benefits. Though not quantitatively estimated in this study, it boosts the revenues of utilities, allows for postponement of investments, and improves customer satisfaction. The complexity of climatic changes to rainfall patterns and the impact on water distribution is not very well known; for this reason, it has been omitted from this analysis.


[1] For more on the Total Addressable Market for the Materials Sector, click the Sector Summary: Materials link below.

[2] For more on Project Drawdown’s three growth scenarios, click the Scenarios link below. For information on Materials Sector-specific scenarios, click the Sector Summary: Materials link.

[3] All monetary values are presented in US2014$.

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