# EPANET Example

A 50 ft diameter tank is located in a city to supply drinking water for a small community. The tank is 20 ft. high and is located 400 ft above the city. The tank supplies water with a constant flow of 4 cfs during the day. All the nodes in the network are located at 0 ft elevation. All the pipes have a roughness coefficient C = 100. Use Hazen-Williams formula during your calculations. Minor losses are neglected.

## Demand Pattern

We assumed at the beginning that there was a constant demand in the city, but that is not accurate. It is possible to create a scenario where each hour is a multiplier from the minimum demand. The demands shown earlier in Figure 2 corresponded to the minimum demands in the city that occurred between midnight and 1 a.m. For the rest of the day, the demand is higher. Typical multiplying factors during each hour are shown in Table 2.

## EPANET SIMULATION

Below is the EPANET version of the above network.

To come to this point, following are the key steps:

Base demand at Junction 1 is negative due to the inflow of 4 cfs water from tank to the J1. J1 has water demand of 0.15 cfs, thus the total demand at this junction is 0.15-4 = 3.85 cfs

After setting up analysis, below are the results of nodes and links.

Demand Pattern

## Pumps

Assume now that the maximum elevation of the tank is reduced to 340 ft. To change the elevation generates negative pressures in the node 17 at 8 a.m. It is desired to add a pump in pipe 21 to increase the head pressure.

## Reservoir

Delete the pump and tank. Assume now that there is no tank. Replace the tank with a reservoir at the same elevation than the city. Because the city and the reservoir are at the same elevation, you will need a Pump to supply the water.