Infiltration of stormwater is now being adopted extensively in various locations throughout Tokyo. The main objectives of infiltration in urban areas are runoff control and groundwater enrichment. The techniques for planning, designing, construction, and maintenance were established, and then the effects of infiltration were proved. This paper will introduce some examples of infiltration structures in Tokyo. All footpath pavements in Tokyo have been changed to permeable pavement. Some of the porous concrete blocks now are made from incinerated sewage sludge or slag of melted sewage sludge. Residents cooperate to construct soakaways in their own housing areas at their own expense. The infiltration trench is so effective that it is used in various locations such as housing sites, housing complexes, streets, school grounds, public gardens. The storage tank can be constructed in a housing complex, thus stored stormwater can be effectively used for toilets, sprinkling, car wash, and for a recreational pond. The reduction of stormwater runoff by infiltration facilities is also greatly effective in preventing contamination of receiving waters.
