Temecula is just like Orange County... except the water is worse

I live right across the Santa Anas from you.
So there are really only two reasonable solutions for our nasty hard water:
(1) Use a reverse osmosis filter.
(2) Get a water softener. If you are using the water for trees, make sure you use potassium chloride instead of sodium chloride to recharge the media.
Decent reverse osmosis units can be had for a few hundred $$$, but at this price point they are really best for limited use (20 gallons per day or less) which is why many homes use them in their kitchen for drinking water and ice cubes. You can use a small filter like this to fill and keep topped off a "rain barrel" in your yard to water some of your more sensitive trees with.
Whole house water softeners will run you somewhere in the $1500 - $2000 range, plus you need a plumber to install them. Make sure the plumber knows you want all your exterior water to run through the softener as well. And you can say goodby to water spots on your glasses or dishes, water spots on your showers, etc.
Both of these solutions require periodic maintenance - the R/O filter will require new cartridges about every 6 months, and the water softener will require you to purchase bags of potassium chloride from your CostCo / Home Depot.