Sustainable water supply of Seoul

Date 2014-05-26 Category Water Supply (Arisu) Updater scaadmin
Young-june Choi
Last Update


The modern water supply system in Seoul began in 1908. However, during the Korean War following the Japanese colonial period, most of the waterworks in the city were severely damaged or destroyed. In 1954, one year after the ceasefire and for the subsequent five years, a waterworks restoration project was launched with the help of UN aid and state funds. During the 1960s and 1970s, demand for water increased exponentially with fast urbanization and industrialization following Korea’s Five-year Economic Development Plans. At this point, the need to expand the water facilities became evident.

Since the amount of water supplied to Seoul at the time was insufficient, the majority of residents endured drinking water shortages. Extra administrative support was particularly needed in vulnerable regions with lower water pressure such as highlands and those near the end of the water supply line. The Seoul Metropolitan Government (SMG) sought to secure funding through foreign aid, the issuance of municipal bonds and state subsidies. These efforts allowed a full commitment to investing in water production and supply facilities and auxiliary water treatment plants.

Thanks to the steady expansion of production facilities and the slowing of population growth, the water supply began to stabilize. By 1988, the service rate had reached 98.8%, rising from 59.8% in 1960. To better supply hillside areas, 122 pressure booster stations had been built by 1989 to mitigate the weak water pressure, and 11 major reservoirs were completed during the three years from 1985 to 1987. Owing to such investments, water storage capacity increased to 648,000 m³: a doubling of the previous capacity.


Large facility investments and extra support in underserved areas brought the service rate in Seoul to 99% by 1989. Following establishment of the groundwork for a reliable supply system, a transition occurred in the policy agenda for waterworks, to "improvement of waterworks management via control of water quality and increase of revenue water ratio (RWR).“ RWR is an indicator to measure the percentage of billed water as a share of net water produced. A higher RWR means less tap water loss, positively affecting the financial viability of water utilities by increasing water sales and cutting unnecessary operating costs. As more people began to consider the quality of tap water rather than simply quantity, technological and administrative means were devised to address these demands.


A higher RWR means greater efficiency in water production and supply, and greater financial benefit in utility management. Enhancing the RWR improves both the quality and quantity. For this reason, the SMG arranged both administrative and technical support to increase it. This technical support by the SMG included:
  • - Construction of reservoirs for balanced water pressure
  • - Replacement of old pipes
  • - Leakage monitoring via a small-scale block system and measurement of minimum night flow
  • - Leakage surveillance
  • - Prioritized management of regions with pressurized water supply
  • - Establishment of GIS with database on locations and materials of pipes.

The administrative improvements include:

  • Creation of a special organization for the RWR improvement project
  • Meticulous evaluation scheme for institutional performance based on RWR
  • Detection of fraudulent activity such as faulty metering and illegal connections.
Seoul was divided into 2,037 small blocks to reduce the amount of non-revenue water by cutting water leakage and improving quality. The pipe network was designed on these block systems, with old pipes repaired or replaced and leaks detected. This facilitated continuous monitoring and repairs of leakage as well as intensive repairs of deteriorating pipes and maintenance of unused ones, helping to reduce water loss in regions with lower RWR.
In the past, pressure boosting was the method of choice to facilitate the supply of water to highlands. However, the unreliability of that pressure was responsible for water hammering and leakage. As a solution, the SMG transformed its plan for water supply to a passive delivery system, undertaking an expansion of service reservoirs that involved the construction of 104 new ones (2,420,000 m³ in total). These efforts paid off, as shown in the increased RWR from the reduced leakage and greater reliability of supply.







Department / Contact

  • Waterworks Research Institute / Choi young-june
  • International Relations Division  /  82-2-2133-5276  /  international@seoul.go.kr
  • City Diplomacy Research Center  /  82-2-2149-1418  /  ssunha@si.re.kr