Fallbrook Water Hardness & Quality Report (2026)

Fallbrook, California, an unincorporated community in San Diego County — a major north inland San Diego County avocado and military community (Fallbrook is the 'Avocado Capital of the World' — an unincorporated San Diego County community in the north inland hills, home of the most productive avocado-growing region in the United States; the Fallbrook area's Mediterranean microclimate (mild temperatures, well-drained decomposed granite soils) is ideal for California Hass avocado production; the Fallbrook Avocado Festival is one of California's most beloved agricultural festivals), adjacent to Camp Pendleton (one of the largest US Marine Corps installations in the country — the primary West Coast USMC training base, adjacent to and surrounding much of north San Diego County), a diverse San Diego County community with a significant military veteran, retiree, and agricultural worker population, and one of the most distinctive agricultural communities in Southern California — draws its municipal water supply via the Rainbow Municipal Water District. Water hardness in Fallbrook measures 149 mg/L — classified as moderately hard.

Fallbrook's moderate hardness reflects the north San Diego County import supply blend characteristics. The Rainbow MWD distributes San Diego County Water Authority supply (Colorado River Aqueduct and State Water Project blend) to the north San Diego County Fallbrook zone (with treatment), producing the moderate 149 mg/L.

At 149 mg/L, Fallbrook residents encounter moderate scale accumulation. Monthly cleaning is recommended. Rainbow Municipal Water District consistently delivers water meeting all California SWRCB and EPA Safe Drinking Water Act requirements.