Stormwater control measures must often be included in the "combined" wastewater and storm water systems found in many parts of Japan.

Source: Making Great Breakthroughs - All about the Sewage Works in Japan (Japan Sewage Works Association: Tokyo, ca. 2002), p. 33.

Diagram showing problems with "combined" sewage systems and improvements in Japan, circa 2002.

Source: Making Great Breakthroughs - All about the Sewage Works in Japan (Japan Sewage Works Association: Tokyo, ca. 2002), p. 34.

Diagram of a stormwater reservoir used in Japan to improve the "combined" sewer system and control flooding.

Source: Making Great Breakthroughs - All about the Sewage Works in Japan (Japan Sewage Works Association: Tokyo, ca. 2002), p. 35.

Diagram showing the use of optical fiber cables for sewerage system management in Japan. Optical cables are allowed in Japanese sewer pipes after the Sewerage Law was revised in 1996.

Source: Making Great Breakthroughs - All about the Sewage Works in Japan (Japan Sewage Works Association: Tokyo, ca. 2002), p. 38.