A city has one million population and water supply to the city is from a reservoir 10 km away. The minimum required water supply is at the rate of 150 litres per head per day. The supply is made in two shifts, each being for 8 hours Duration. The full supply level of the reservoir is R.L. 180.00 and its lowest level is R.L. 105.00. The delivery end of the main is at R.L. 22.5 m. The head loss at the delivery of the main is 12 m. Find the diameter of the pipe required. Assume friction factor equal to 0.04.