Riverside County's rapidly expanding fire hazard zones and rural development patterns make fire water storage a critical requirement for many properties. Ordinance 787.11 — adopted December 2025 — brings the county's fire code in line with the new 2025 California WUI Code, with a 1,500 GPM minimum for WUI subdivisions.
A private fire suppression water storage tank is required when any of these conditions apply:
| Condition | Sizing Method | Minimum Tank Size |
|---|---|---|
| No exposure hazards (no adjacent structures within 100 ft) | NFPA 1142 formula | 2,000 gal minimum |
| With exposure hazards (adjacent structure within 100 ft) | NFPA 1142 formula | 3,000 gal minimum |
| With NFPA 13D sprinklers installed | 50% reduction of NFPA 1142 calc | 50% credit (2,000/3,000 gal floor) |
| WUI subdivision (new tracts) | Ord. 787.11, §B103.2.1 | 1,500 GPM minimum fire flow |
Tank sizing uses the NFPA 1142 formula: MWS = (Structure Volume ft³ × Construction Classification Number) ÷ Occupancy Hazard Classification. The 2,000/3,000 gallon minimums are absolute floors — actual calculations for typical homes often yield 5,000–10,000+ gallons. A 50% volume credit is available when NFPA 13D sprinklers are installed.
On March 24, 2025, the Office of the State Fire Marshal issued updated Local Responsibility Area FHSZ maps for Riverside County, designating areas as Moderate, High, or Very High. These maps must be formally adopted within 120 days.
Riverside County has taken significant regulatory action in the 2025–2026 period:
Rural commercial properties can use NFPA 1142 calculations under OFM-01B guidelines, providing flexible approaches for remote sites. Industrial facilities and large commercial operations in western Riverside County must meet standard IFC Appendix B fire flow requirements.
We serve commercial, industrial, and institutional clients across the region — from data centers and manufacturing plants to schools, hotels, and healthcare facilities. View our full commercial & industrial fire water storage page →
Tank Specialists of California has 30+ years of experience installing fire suppression water storage systems. As an authorized Pioneer Water Tanks dealer, we handle everything — from fire code analysis and permitting to foundation, tank assembly, and final inspection.
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