For customers in locations with warmer groundwater, we recommend some specific best practices to help with your chilling efficiency. Our testing for the below recommendation was done using 82F groundwater.
Start by adding 12lbs of ice to 5 gallons of tap water and give the water a couple stirs as the ice melts.  Run the chiller off of a garden hose spigot fully open to 10F above your tap water temperature (92F in this example). Then switch over to a utility pump submersed in the ice water that you have ready and run the bucket dry. We recommend a utility pump because the pump needs to have enough head pressure to push a large volume of water through the chiller, whereas a pond or aquarium pump typically won’t have enough head pressure to push water through when a restriction, such as a wort chiller, is put on the end.  Our testing with this setup was able to chill 5 gallons of wort to 70F in 5 minutes using 82F tap water.
Also, remember to only pump the ice water through once in order to have the largest temperature differential between your chilling water and the wort.