
The best way to measure your incoming ground water temperature is to use a thermometer to measure cold water temperature during the coldest season of the year. To simplify the process, use this map to determine whether your installation location is in the Southern Zone, Central Zone or Northern Zone. Average Ground Water Temperatures SOUTHERN ZONE A v er age Ground W ater T emper atur e: 62°F to 77°F CENTRAL ZONE A v er age Ground W a ter T emper atur e: 52°F to 61°F NORTHERN ZONE A v er age Gro