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Press Release

FY 2003 Dissemination Status of Johkasoh

August 20, 2004

Dissemination status of johkasoh, on-site treatment system of domestic wastewater

The Ministry of the Environment (often referred to as the "MoE"), the Ministry of Agriculture, Forestry and Fisheries and the Ministry of Land, Transportation and Infrastructure have jointly released since 1996 the dissemination status of wastewater treatment facilities including johkasoh and community wastewater treatment plants, rural sewage systems and sewage systems, respectively managed by the three ministries. Number of people served with these wastewater treatment facilities is 98.54 million, 77.7% of the total population (dissemination ratio) as of the end of FY 2003 (March 31, 2004). Total number of people using johkasoh is 10.3 million and the dissemination ratio is 8.1%.

Features of johkasoh

Johkasoh is an on-site treatment system of domestic effluent which includes human wastes installed at each household and its treated water is discharged to the nearest public water area. Johkasoh has the following features.
(i)    Treatment capability is the same as that of wastewater treatment facility of sewage system.
  • Removal rate of biological oxygen demand (BOD) is 90% or more.
  • BOD of treated water is less than 20mg/l.
(ii)    Installation expense is approximately 900,000 yen for a system for five persons, which is comparatively low.
(iii)    Duration of installation is one week to ten days, which means investment efficiency, becomes apparent in an early stage.
(iv)    The system is easy to install, regardless of the geological formation.
(v)    The system utilizes natural purification capacity of small rivers and contributes securing water volume of them.

Promotion of installation of johkasoh

The MoE established the Johkasoh Promotion Program in FY1987. In this program, the MoE provides subsidies to the local municipalities that are subsidizing installation expense to the citizens who will install a johkasoh.

The MoE also developed the Municipal Johkasoh Promotion Program, in which local municipalities themselves install and maintain the johkasoh in 1994. The MoE has been promoting this program, since steady maintenance of johkasoh is ensured by municipalities through this program. In the supplementary budget of FY2002, the area for subsidies was expanded to those in which improvement of johkasoh is more economic and efficient compared to collective wastewater treatment systems including sewage. Number of municipalities carry out the program has increased from 175 municipalities as of January 2003 to 217 as of April 2004. The MoE would further promote this program.

FY 2003 Population Using Johkasoh and Dissemination Rate
  As of March 31, 2004 As of March 31, 2003 Difference between FY 2002 and FY 2003
Population increased Rate of increase
Population using
10.3 million 9.93 million 360,000 3.7%
Rate of increase 8.1% 7.8% 0.3% -
Notes:    1.   Dissemination ratio is the ratio of population using johkasoh to total population.
  2.   Population figures are rounded off to the nearest 10,000. Difference may not add up due to round off.

* FY 2003 Population Covered by Wastewater Treatment Facilities
* FY 2003 Dissemination Rate of Johkasoh by City Scale

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