Consider a small water reservoir at the exit of a water treatment plant with an operating capacity of 6 ML (mega litres). When the water reservoir is below operating capacity it receives a constant inflow rate of 2.0 ML/hour from a water treatment plant. When the reservoir is full, the delivery from the water treatment plant is stopped so the reservoir does not exceed its operating capacity. The water from the reservoir is delivered to a suburb whose demand profile is: Offpeak period - From 11:00 pm to 7:00 am the demand rate is 0.45 ML/hour. Peak period - From 7:00 am to 11:00 pm the hourly demand rate follows a log-normal distribution with a mean of 2.6 ML/hour and a coefficient of variation of 0.4. The demand from hour to hour can be considered statistically independent