💧 FIRE

Fire Water Storage Tank Calculator (NBC Part 4)

Calculate total fire water storage for hydrant and sprinkler systems. NBC Part 4 / IS 15105 compliant. Fire reserve sizing for Indian buildings.

📐 Standard: NBC Part 4 / IS 15105
✅ Free to use
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ℹ️ About This Calculator

NBC 2016 Part 4 requires every building above 15m height or with specified occupancy to have a dedicated fire water reserve sufficient for combined hydrant and sprinkler operation. This tank must be exclusive to fire fighting use — domestic water supply must not reduce the fire reserve. The fire water tank is separate from the domestic water storage and must be accessible to the fire brigade.

NBC Part 4 and TAC (Tariff Advisory Committee) guidelines govern fire water storage for insurance compliance. Most insurance companies in India require TAC-compliant fire protection systems for coverage. The fire water tank inlet must be fitted with a ballcock valve that shuts off at high level. A dedicated fire water pump with auto-start on pressure drop, jockey pump for pressure maintenance, and a diesel standby pump (for power failure) is mandatory for buildings requiring NBC Part 4 compliance.

📐 Fire Water Reserve Calculation (NBC Part 4)

NBC Part 4 / IS 15105

Total Fire Reserve = V_hydrant + V_sprinkler

Hydrant System Demand:
  Flow: 900–2700 L/min (by occupancy and height)
  Duration: 30–60 minutes
  V_hydrant = Flow (L/min) × Duration (min)

Sprinkler System Demand (IS 15105):
  Light Hazard: 450 L/min × 30 min = 13,500 L
  Ordinary Hazard 1: 900 L/min × 60 min = 54,000 L
  Ordinary Hazard 2: 1350 L/min × 60 min = 81,000 L
  High Hazard: 2250 L/min × 90 min = 202,500 L

Pump Sizing:
  Duty pump: rated at design flow and pressure
  Jockey pump: 10% of duty pump flow
  Standby: 100% of duty pump (diesel driven)

❓ Frequently Asked Questions

What is the fire water requirement for a G+10 commercial building? +
For a 10-floor commercial office (ordinary hazard group 1): Hydrant demand = 1800 L/min × 60 min = 108,000 L = 108 KL. Sprinkler demand = 900 L/min × 60 min = 54 KL. Total fire reserve = 108 + 54 = 162 KL. In practice, the fire consultant often specifies 180–200 KL after applying safety factors. This is in addition to the domestic water storage.
Can I use the domestic water tank for fire water in an emergency? +
No — NBC Part 4 requires fire water to be stored separately in a dedicated tank. The fire water reserve must not be accessible to domestic supply systems. The purpose is to ensure the fire reserve is always available for fire fighting, regardless of domestic water demand. Fire water tanks must be visually identifiable and prominently labeled as "FIRE WATER — DO NOT USE FOR OTHER PURPOSES".
How high above ground should the fire water tank be? +
NBC Part 4 requires the bottom of the overhead fire water tank to be at sufficient elevation to provide minimum 0.7 bar (7m head) at the highest hydrant outlet, or the fire pump takes suction from an underground tank. Most buildings use an underground fire water sump with electric and diesel fire pumps that pressurize the system on demand. Roof-level tanks without pumps are only suitable for buildings where gravity provides sufficient pressure.
What is the role of the jockey pump in a fire system? +
The jockey pump (also called pressure maintenance pump) is a small pump that runs continuously to maintain system pressure. When the system loses pressure due to a minor leak or head faucet operation, the jockey pump repressurizes it without starting the main fire pump. If pressure drop is too large for the jockey pump (i.e., a fire has started), the main duty fire pump auto-starts. Jockey pump flow is typically 10% of the duty pump.
Does the fire water tank need to be tested regularly? +
Yes. NBC Part 4 requires annual hydraulic testing of the fire fighting installation. The fire water tank level should be checked monthly. Fire pumps should be run weekly (jockey pump continuously) and tested quarterly at full flow. Test all sprinkler heads, hydrant hose reels and cabinets annually. Maintain a test register — fire authorities can inspect it during NOC renewal.

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💧 Fire Water Tank Calculator
Reference: NBC Part 4 / IS 15105