Tanks

Fire Water Tank Sizing (NFPA 22)

Fire water storage tanks must meet NFPA 22 requirements for capacity, reliability, and configuration. Here is how Plumbing Booster handles NFPA 22-compliant sizing.

Plumbing Booster fire water tank sizing screen

Introduction

NFPA 22 (Standard for Water Tanks for Private Fire Protection) governs the design, construction, and sizing of fire water storage tanks. These tanks provide a dedicated water reserve for fire suppression systems (sprinklers, hoses, hydrants). Plumbing Booster implements NFPA 22 sizing methodology with the full standard extracted as reference data.

Methodology

Fire water tank sizing per NFPA 22: 1. **Determine fire protection demand** - Sprinkler system flow rate + hose stream flow rate. 2. **Determine duration** - NFPA specifies minimum duration based on hazard classification (typically 30-120 minutes). 3. **Calculate required volume** - Flow rate x Duration. 4. **Add reserve** - Some jurisdictions require additional reserve for hose streams or multiple fire events. 5. **Consider tank configuration** - Dedicated fire tank or combined domestic/fire tank with separate fire reserve. 6. **Check reliability requirements** - NFPA 22 specifies tank filling time, overflow, and level monitoring.

Code References

**NFPA 22 (2023)** - Standard for Water Tanks for Private Fire Protection: - Chapter 4: General Requirements - Chapter 5: Tank Capacity and Dimensions - Chapter 6: Tank Materials and Construction - Chapter 10: Filling and Overflow **NFPA 13** - Sprinkler system design (determines flow rate and duration) **NFPA 14** - Standpipe and hose system design

Worked Example

A light-hazard office building: - Sprinkler design flow: 500 GPM - Hose stream allowance: 100 GPM - Total fire flow: 600 GPM - Duration (light hazard): 30 minutes - **Required volume: 600 x 30 = 18,000 gallons** Tank selection: 20,000-gallon atmospheric tank (next standard size up). Refill time: Must be filled within 8 hours (NFPA requirement) -> minimum fill rate = 20,000/8 = 2,500 GPH.

How Plumbing Booster Automates It

The Water Supply Tanks module includes NFPA 22 as a reference data source. Select "Fire Water (NFPA 22)" as the tank type, enter fire protection demand and duration, and the software calculates required volume, recommends tank dimensions, and verifies NFPA 22 compliance. The full NFPA 22-2023 standard text is available as extracted reference data.

Tank Sizing Methodology

Water supply tank sizing ensures adequate storage for domestic demand, fire protection, expansion, and pressure maintenance. Here is the methodology.

Domestic Water Demand Calculation

Domestic water demand calculation is the foundation of plumbing system design. This guide covers WSFU summation, diversity factors, and code-specific flow conversion.