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 ZoneEfficiency
+71 °F100% (8 GPM)
61 – 70 °F73% (5.8 GPM)
51 – 60 °F58% (4.6 GPM)
41 – 50 °F48% (3.8 GPM)
< 40 °F41% (3.2 GPM)

 

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.

California Groundwater Temperature Yearly Average

City & Zip CodesGroundwater 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

Burbank

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

Los Angeles

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

Mecca

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

Sacramento

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 zoneRecommended Tankless Water Heater
< 40 °FTankless Water Heater Recommendations
41 – 50 °FTankless Water Heater Recommendations
51 – 60 °FTankless Water Heater Recommendations
61 – 70 °FTankless Water Heater Recommendations
+71 °FTankless Water Heater Recommendations