Rainwater Utilization within Tokyo ’ s Sumida City Utilizing Rainwater to Save the Earth

How Rainwater Utilization Works Flush toilet Rainwater storage tank Flush toilet Lifting pump Filtration Washing the car Rainwater storage tank Overflow water Watering the plants Soaks into the ground

Aim of Rainwater Utilization: Prevention of Urban Flooding

Second Aim of Rainwater Utilization: Water Resources Measure

Third Aim of Rainwater Utilization: Disaster Prevention Measure

Tokyo's Ryogoku Kokugikan

ROJISON No. 2

Sumida City Office

Tokyo International Rainwater Utilization Conference (August 1994)

Rainwater Utilization Promotion Guidelines (April 1995) 1 As a rule, city facilities will make use of rainwater utilization equipment. 2 The private sector will be offered guidance in adopting rainwater utilization. ⇒ Sumida City Development Guidelines (from Dec. 1995) ⇒ Apartment and Condominium Housing Ordinance (from July 2008) 3 Private sector rainwater storage tank installation will be subsidized. ⇒ Subsidy System for Rainwater Utilization Promotion (from October 1995)

Subsidy System for Promotion of Rainwater Utilization 1 Underground beam-type storage tank (5m 3 or more) 40,000 yen per 1m 3 ; maximum of 1 million yen 2 Medium storage tank (1m 3 or more); maximum of 300,000 yen Fiber Reinforced Plastic (FRP) or stainless steel: 120,000 yen per 1m 3 High-density polyurethane: 45,000 yen per 1m 3 3 Small storage tank (under 1m 3 ) ½ of tank cost; maximum of 40,000 yen Limited to city-specified tanks.

Rainwater Tanks

Target Structures and Requirements Designated by Guidelines and Ordinance 1 Target Structures Apartment and condominium housing (15 or more total housing units, 1,000m 2 or more total floor space, five or more stories high) Large buildings (1,000m 2 or more total floor space), etc. 2 Requirements Site area under 500m 2 : pavement infiltration, etc. Site area of 500m 2 or more: pavement infiltration, etc. + rainwater utilization

Sumida City Rainwater Utilization Network (1) 1 Liaison Committee of Local Authorities Promoting Rainwater Utilization Begun in July 1996 Includes 133 local authorities Rainwater storage tank installation subsidy: 66 local authorities Septic tank conversion subsidy: 28 local authorities Underground seepage subsidy: 38 local authorities (as of December 2009)

Sumida City Rainwater Utilization Network (2) 2 Residents People for Rainwater NPO 3 Organizations, Societies, etc. Association for Rainwater Storage and Infiltration Technology, Architectural Institute of Japan, etc. 4 Rainwater Network A loose-knit network of industry, academia and government

Facilities Employing Rainwater Utilization