Fort Bliss, a U.S. Army military base, contributed $3.3 million

Fort Bliss, a U.S. Army military base, contributed $3.3 million of the $87 million capital cost for a desalting plant constructed and operated by El Paso Water Utilities (EPWU). In return, EPWU agreed to sell water to Fort Bliss at $0.85 per 1000 gallons for 20 years. If the army base uses 200 million gallons of water per month, what is the Army's cost per month for water? The $3.3 million capital cost is amortized at an interest rate of 6% per year, compounded monthly.