Hard water at 20 grains per gallon
El Centro water measures around 340 to 350 mg/L - roughly 20 grains per gallon, well past the threshold where water heaters, faucets, and valves start to scale and seize. At that level, a tank water heater without a softener typically survives 6 to 8 years instead of the 12 a national parts catalog assumes.
We size softeners for the home's actual hardness and usage, not the average the box came with. When a water heater is replaced, we look at the bottom of the old tank first - if the scale is more than an inch thick, the cause is the supply, not the heater, and we say so.
Reverse osmosis at the kitchen tap is the second standard fix in this valley. Imperial Valley water also pulls in some arsenic and nitrates from agricultural runoff, so the right drinking-water setup is rarely just a softener. We install both and we maintain both.