California
Average Groundwater Temperatures for the Cities in California
Temperature is important to consider when dealing with hard water because calcium dissolves more easily in cold water. Most substances that dissolve in water, such as sugar, do not behave in this manner. It is common knowledge that you can dissolve more sugar in hot water than cold. Calcium has the opposite effect: the hotter the water, the less calcium it can dissolve. If your water source is deep in the earth (higher pressure also contributes to increased calcium solubility) and the groundwater is very cold, you can almost certainly expect hard water. Groundwater is so hard in some areas that water utilities must blend it with surface water to reduce the hardness. If you would like more information on the hard water levels in your area please see our hard water map.
Another important reason to know your average groundwater temperatures is if you are trying to determine which tankless water heater to purchase. The reason for this is because in colder climates the groundwater 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 must be able to raise the temperature of the water by 58°F while still providing adequate flow to support the fixtures you wish to run at the same time.
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) |
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.
California Groundwater Temperature Yearly Average
| City & Zip Codes | Groundwater Temperatures |
|---|---|
Anaheim 92804 | 92805 | 92801 | 92802 | 92806 | 92807 | 92808 | 63°F |
Bakersfield 93307 | 93306 | 93312 | 93309 | 93308 | 93313 | 93304 | 93311 | 93305 | 93314 | 93301 | 64°F |
91501 | 91502 | 91504 | 91505 | 91506
| 64°F |
Chula Vista 91911 | 91910 | 91913 | 91915 | 91914 | 62°F |
Corona 92882 | 92880 | 92879 | 92883 | 92881 | 62°F |
Coachella 92236 | 68°F |
Fontana 92355 | 92336 | 92337 | 62°F |
Fremont 94536 | 94538 | 94539 | 94555 | 61°F |
Fresno 93722 | 93727 | 93720 | 93702 | 93726 | 93706 | 93711 | 93705 | 93703 | 93710 | 93704 | 93725 | 93728 | 93723 | 93730 | 93701 | 93721 | 93650 | 62°F |
Fullerton 92833 | 92831 | 92832 | 92835 | 62°F |
Garden Grove 92840 | 92843 | 92841 | 92844 | 92845 | 64°F |
Glendale 91205 | 91206 | 91201 | 91202 | 91204 | 91208 | 91203 | 91207 | 91210 | 61°F |
Huntington Beach 92647 | 92646 | 92648 | 92649 | 62°F |
Irvine 92620 | 92618 | 92612 | 92604 | 92614 | 92602 | 92606 | 92603 | 92617 | 59°F |
Long Beach 90805 | 90813 | 90806 | 90815 | 90802 | 90804 | 90808 | 90810 | 90803 | 90807 | 90814 | 90822 | 90831 | 62°F |
90011 | 90044 | 90003 | 90026 | 90019 | 90022 | 90037 | 90042 | 90006 | 90004 | 90066 | 90001 | 90034 | 90018 | 90002 | 90063 | 90046 | 90024 | 90057 | 90047 | 90025 | 90065 | 90032 | 90033 | 90023 | 90016 | 90059 | 90027 | 90043 | 90007 | 90045 | 90005 | 90020 | 90031 | 90036 | 90029 | 90049 | 90012 | 90062 | 90008 | 90028 | 90039 | 90041 | 90035 | 90038 | 90061 | 90017 | 90064 | 90048 | 90015 | 90068 | 90040 | 90013 | 90077 | 90014 | 90056 | 90089 | 90010 | 90021 | 90058 | 90067 | 90073 | 90071 | 90079 | 90095 | 62°F |
92254 | 71°F |
Menifee 92584 | 92585 | 92586 | 92587 | 68°F |
Mendocino 95460 | 68°F |
Modesto 95355 | 95350| 95351 | 95358 | 95356 | 95354 | 95357 | 62°F |
Oakland 94601 | 94602 | 94603 | 94605 | 94606 | 94607 | 94609 | 94610 | 94611 | 94612 | 94613 | 94618 | 94619 | 94621 | 62°F |
Oceanside 92057 | 92056 | 92058 | 92054 | 58°F |
Orange 92867 | 92869 | 92868 | 92865 | 92866 | 62°F |
Oxnard 93033 | 93030 | 93036 | 93035 | 63°F |
Pasadena 91104 | 91107 | 91103 | 91106 | 91101 | 91105 | 62°F |
Redding 96003 | 96001 | 96002 | 96049 | 63°F |
Riveside 92503 | 92504 | 92507 | 92505 | 92506 | 92508 | 92501 | 59°F |
Roseville 95661 | 95678 | 95747 | 62°F |
95823 | 95828 | 95822 | 95831 | 95833 | 95835 | 95838 | 95826 | 95825 | 95820 | 95821 | 95842 | 95824 | 95834 | 95829 | 95815 | 95864 | 95818 | 95827 | 95841 | 95819 | 95816 | 95817 | 95832 | 95814 | 95811 | 95830 | 95837 | 94574 | 63°F |
Salinas 93906 | 93905 | 93901 | 93907 | 93908 | 62°F |
San Diego 92154 | 92126 | 92105 | 92114 | 92115 | 92117 | 92113 | 92130 | 92129 | 92128 | 92111 | 92127 | 92122 | 92109 | 92104 | 92102 | 92101 | 92139 | 92103 | 92131 | 92116 | 92124 | 92123 | 92107 | 92110 | 92120 | 92119 | 92108 | 92106 | 92121 | 92140 | 92145 | 92135 | 92147 | 92155 | 92134 | 92132 | 65°F |
San Clemente 92672 | 92673 | 65°F |
San Francisco 94112 | 94110 | 94122 | 94109 | 94116 | 94117 | 94121 | 94134 | 94118 | 94124 | 94115 | 94114 | 94132 | 94102 | 94131 | 94107 | 94103 | 94133 | 94123 | 94127 | 94108 | 94105 | 94158 | 94129 | 94111 | 94130 | 94104 | 94128 | 57°F |
San Jose 95123 | 95127 | 95111 | 95112 | 95122 | 95116 | 95125 | 95124 | 95148 | 95136 | 95132 | 95129 | 95121 | 95120 | 95128 | 95126 | 95118 | 95131 | 95117 | 95133 | 95134 | 95135 | 95138 | 95110 | 95130 | 95119 | 95139 | 95113 | 66°F |
Santa Barbara 93101 | 93105 | 93103 | 93111 | 93110 | 93109 | 93108 | 62°F |
Santa Maria 93453 | 93458 | 93455 | 93454 | 61°F |
Santa Monica 90405 | 90403 | 90404 | 90402 | 90401 | 62°F |
Stockton 95206 | 95207 | 95209 | 95210 | 95205 | 95219 | 95204 | 95212 | 95215 | 95203 | 95202 | 95211 | 62°F |
Sunnyvale 94087 | 94086 | 94085 | 94089 | 63°F |
Temecula 92592 | 92591 | 92590 | 65°F |
Turlock 95380 | 95382 | 68°F |
Tustin 92780 | 92782
| 67°F |
Union City 94587 | 62°F |
Upland 91784 | 91786 | 63°F |
Vacaville 95687 | 95688 | 63°F |
Valencia 91354 | 91355 | 65°F |
Vallejo 94589 | 94590 | 94591 | 62°F |
Ventura 93001 | 93003 | 93004 | 65°F |
Victorville 92392 | 92394 | 92395 | 63°F |
Visalia 93277 | 93291 | 93292 | 65°F |
Vista 92081 | 92083 | 92084 | 65°F |
Walnut Creek 94595 | 94596 | 94597 | 94598 | 61°F |
Watsonville 95076 | 63°F |
West Corvina 91790 | 91791 | 62°F |
West Sacramento 95605 | 95691 | 62°F |
Westminster 92683 | 65°F |
Whittier 90601 | 90602 | 90603 | 90604 | 90605 | 90606 | 65°F |
Woodland 95695 | 95776 | 66°F |
Yorba 92886 | 92887 | 65°F |
Yuba City 95991 | 95993 | 65°F |
What Tankless Water Heater Should you Buy if you Live in California?
Since California’s average temperature range is between 58°F and 68°F. It is recommended that you select a green zone or orange zone Tankless Water Heater. To see the recommended Tankless Water Heaters that apply to the green and orange zone temperatures please follow the link that corresponds to the region of your average city 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 |
