We have to revalidate the design of the network system consisting of Transmission main(s), feeder main(s) and distribution network system of a city using Watergems. The system consists of Transmission main(s), feeder main(s) with Intake sump, WTP clear water sumps, Booster station, mass balancing reservoirs, Ground level service reservoirs and over head tanks supplied by both gravity and pumping. Whether these closed Intake sump, WTP clear water sumps, Booster station, mass balancing reservoirs and Ground level service reservoirs be a reservoir element in the model or only tank element?. I feel that unless the supply is from a dam these elements should be designed with a tank element only.