South Dakota

Average Groundwater Temperatures for the Cities in South Dakota

Average groundwater temperatures play an important role in determining which tankless water heater to purchase. The reason for this is because in colder climates the groundwaters starting temperature is colder than in warmer climates. This causes the tankless water heater to work harder to increase the water temperature in colder climates, which in turn causes the flow rate to decrease in parallel. For example, if the starting water temperature is 52°F and you need to raise the water temperature to 110°F. Then your tankless water heater needs to be capable of raising the water temperature by 58°F and still have enough flow to support the fixtures you want to simultaneously run.


How Flow Rates are Affected by Temperature

In the example below, you can see the impact that temperature has on flow rates. This example is based on a tankless water heater that has a flow rate rated for 8 GPM.


Temperature Zone Efficiency
+71 °F 100% (8 GPM)
61 - 70 °F 73% (5.8 GPM)
51 - 60 °F 58% (4.6 GPM)
41 - 50 °F 48% (3.8 GPM)
< 40 °F 41% (3.2 GPM)

The efficiency percentage is an average based on Siebel TempraRinnai RU199, and ECO90 tankless water heater models.


Flow Rates of Appliances

Based on the corresponding flow rates for each appliance that are listed. A tankless water heater that is rated with a flow rate of 8 GPM (gallons per minute) is capable of running these items at the same time in regions with an average groundwater

temperature of 72°F.


Shower = 3 GPM

Kitchen Sink = 1.5 GPM

Washing Machine = 2.5 GPM

Total = 7 GPM


If you take this same exact tankless water heater and install it in a region that has an average groundwater temperature of 52°F (green zone). This will lower that tankless water heater's max GPM output to 4.64 GPM.


Shower = 3 GPM

Kitchen Sink = 1.5 GPM

Total = 4.5 GPM


As you can see before purchasing a tankless water heater it's important to know the impact temperature has on its ability to heat water and its effect on the total GPM needs of your household.


South Dakota Groundwater Temperature Yearly Average


City and Zip Codes Groundwater Temperatures

Sioux Falls

57103 |57104 | 57105 | 57106 | 57107 | 57108 | 57110 | 57117 | 57197 


Rapid City

57701 | 57702 | 57703












What Tankless Water Heater Should you buy if you Live in South Dakota?

Since South Dakota's average groundwater temperature range is between 45°F and 47°F. It is recommended that you select a light blue zone Tankless Water Heater. To see the recommended Tankless Water Heaters that apply to the light blue and green zone temperatures please follow the link that corresponds to the region of your average groundwater temperature.


Temperature zone Recommended Tankless Water Heater
< 40 °F Tankless Water Heater Recommendations
41 - 50 °F Tankless Water Heater Recommendations
51 - 60 °F Tankless Water Heater Recommendations
61 - 70 °F Tankless Water Heater Recommendations
+71 °F Tankless Water Heater Recommendations