Water is animportant element oflife, hence must be preserved. In addition, thepricing of water supply must be consistent and optimal to ensure its sustainability. Thispaperdescribes thedynamic model in the forms of mathematical (structural)equations translatedfrom the Regulation of the Minister of Domestic AffairsIndonesia,No.23 Year2006. This regulation has been used by Perusahaan Daerah Air Minum (PDAM) Tirtanadi Medan, North Sumatera in determiningthe water price. Themodel consists ofseveraleconomic variables such as minimum wage, inflation,and subsidy that majorly influencedthe forecasted water price
