California Land & Building Basics

Buying rural or unimproved land in California — or building on what you own — comes with a due-diligence checklist beyond the price: can it support a septic system, is there water, what's the soil, and what can you build? These California-specific guides cover the tests, costs, and county and state rules, and tie back to how each choice affects your property tax.

Perc Test in CaliforniaThe soil-drainage test that decides whether unsewered land can support a septic system.Septic System Cost in CaliforniaConventional vs. engineered systems, the perc test, and county permits — typical CA ranges.How Deep Are Wells in California?Typical depths, drilling cost, county permits, and how to look up a parcel's well.California Soil Map & TypesFind any parcel's soil for free — and why drainage and expansive clay drive your costs.California ADU LawsState rules for adding a unit — and the blended property-tax reassessment it triggers.

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What Triggers a ReassessmentHow building on your land changes property tax.The Williamson ActLower property tax for farm and open-space land.Property Tax Rate by CountyThe ongoing carrying cost of land, by county.California Property Tax CalculatorEstimate the tax on land or a new build.