Increasing populations in urban areas including river edge area of the Yogyakarta has environmentally impacted the city river. The most densely populated areas are pushing the use of the land. The land is limited so that each household has only a small piece of land or less, equal to about 60 m2 per house. With these conditions having a home toilet is very uncommon in order to solve this issue, the community has built a communal toilet at the edge of the riverside. This is causing the black water of the public toilet to be directly discharged into the river which therefore is impacting the pollution of the water. The main pollutant of this black water is a bacteria known as Coli (Ecoli) containing above safe health level