UN Earth Summit+5 Success Stories - Local Agenda 21 -Rainwater Storage and Utilization

EARTH SUMMIT+5
Special Session of the General Assembly to Review and Appraise
the Implementation of Agenda 21
New York, 23-27 June 1997
SUCCESS STORIES FROM ASIA AND THE PACIFIC

Rainwater Storage and Utilization This and other Local Agenda 21 succes story are provided by the International Council for Local Environmental Initiatives (ICLEI).

Location Sumida, located in the eastern section of the Tokyo Metropolitan Area, Japan.

Responsible organization City of Sumida.

Description The Municipality of Sumida introduced different rainwater management measures to solve the water shortages and flooding problems.
A Municipal study showed that rainwater was safe for non-drinking purposes and could be used for drinking if sterilized. Given these results, rainwater utilization has since been incorporated into the city's operations and has been recommended to private institutions. Rainwater is collected on roofs and is directed to below ground storage tanks through a net, a basket or a precipitation box to prevent dirt and other debris from getting into the tank. The water is then pumped to a delivery tank located on the roof or on a higher level floor (in order to increase the pressure) where it is directed to the plumbing system. Stored rainwater is generally used to supply water for toilets. To avoid problems during the dry season, rainwater users are encouraged to connect to the municipal water system to prevent shortages in the building. Several homes, businesses, and institutions, including City Hall, have now installed the relatively inexpensive rainwater collection and storage systems. Costs are typically recovered within ten years through savings on city water fees. The city has also begun to install community-level rainwater collection systems which will provide water for fire fighting and drinking in case of emergency.

Issues addressed Water management.

Objectives
Promote local, self-supporting water supplies;
Prevent flooding;
Address disaster relief;
Restore the urban water cycle by returning rainwater to local underground aquifers.

Results achieved Resurfacing sidewalks with permeable pavement to allow for more groundwater recharge. One sixth of the city's sidewalks are currently permeable and the city is planning to convert all sidewalks to permeable pavement.
Establishment of rainwater storage and utilization systems.

Lessons learned The technology for rainwater utilization is relatively simple, inexpensive and highly transferable. These technologies are especially appropriate for cities located in regions which have alternating rainy and dry seasons, and which suffer from flooding, water shortages, land subsidence, and/or restricted local water supplies. Implementing rainwater utilization requires acceptance by municipal officials as well as cross-departmental cooperation and coordination. Educational campaigns are necessary to make local residents and businesses aware of the potential benefits and long-term cost savings.

Financing The cost of installing a rainwater storage and utilization facility was financed out of the budgets of the municipal departments that constructed these facilities in their buildings. Individual homeowners and private companies finance these systems independent of the municipality. The resurfacing of city sidewalks was financed from the operational budget of the Department of Civil Engineering.

Contact Planning Division, Policy Planning Department, Sumida City Office: 1-23-20, Asumabashi, Sumida City, Tokyo 130, Japan; Tel: +81-3/5608-6231, Fax: +81-3/5068-6407

Copyright © United Nations
Department of Economic and Social Affairs
Comments and suggestions: esa@un.org
1 November 1997

	Rainwater Storage and Utilization This and other Local Agenda 21 succes story are provided by the International Council for Local Environmental Initiatives (ICLEI).
	Location	Sumida, located in the eastern section of the Tokyo Metropolitan Area, Japan.
	Responsible organization	City of Sumida.
	Description	The Municipality of Sumida introduced different rainwater management measures to solve the water shortages and flooding problems. A Municipal study showed that rainwater was safe for non-drinking purposes and could be used for drinking if sterilized. Given these results, rainwater utilization has since been incorporated into the city's operations and has been recommended to private institutions. Rainwater is collected on roofs and is directed to below ground storage tanks through a net, a basket or a precipitation box to prevent dirt and other debris from getting into the tank. The water is then pumped to a delivery tank located on the roof or on a higher level floor (in order to increase the pressure) where it is directed to the plumbing system. Stored rainwater is generally used to supply water for toilets. To avoid problems during the dry season, rainwater users are encouraged to connect to the municipal water system to prevent shortages in the building. Several homes, businesses, and institutions, including City Hall, have now installed the relatively inexpensive rainwater collection and storage systems. Costs are typically recovered within ten years through savings on city water fees. The city has also begun to install community-level rainwater collection systems which will provide water for fire fighting and drinking in case of emergency.
	Issues addressed	Water management.
	Objectives	Promote local, self-supporting water supplies; Prevent flooding; Address disaster relief; Restore the urban water cycle by returning rainwater to local underground aquifers.
	Results achieved	Resurfacing sidewalks with permeable pavement to allow for more groundwater recharge. One sixth of the city's sidewalks are currently permeable and the city is planning to convert all sidewalks to permeable pavement. Establishment of rainwater storage and utilization systems.
	Lessons learned	The technology for rainwater utilization is relatively simple, inexpensive and highly transferable. These technologies are especially appropriate for cities located in regions which have alternating rainy and dry seasons, and which suffer from flooding, water shortages, land subsidence, and/or restricted local water supplies. Implementing rainwater utilization requires acceptance by municipal officials as well as cross-departmental cooperation and coordination. Educational campaigns are necessary to make local residents and businesses aware of the potential benefits and long-term cost savings.
	Financing	The cost of installing a rainwater storage and utilization facility was financed out of the budgets of the municipal departments that constructed these facilities in their buildings. Individual homeowners and private companies finance these systems independent of the municipality. The resurfacing of city sidewalks was financed from the operational budget of the Department of Civil Engineering.
	Contact	Planning Division, Policy Planning Department, Sumida City Office: 1-23-20, Asumabashi, Sumida City, Tokyo 130, Japan; Tel: +81-3/5608-6231, Fax: +81-3/5068-6407