Fire Water Storage Tank | NFPA 22 & EN 12845 | ZENTVO
ZENTVO fire water storage tank farm — large-volume outdoor installation
Fire Protection · Emergency Reserve · Code-Engineered

Fire Water
Storage Tank

The dedicated emergency water reserve that feeds sprinklers, hydrants, hose reels or fire pumps. Sized by code-mandated demand × duration — not by ordinary water demand. Supplied to NFPA 22, EN 12845, FM Global DS 3-2, LPCB LPS 1276 and BS 9990.

Request a 24-hour Quote See Capacity Calculations
NFPA 22 EN 12845 FM Global DS 3-2 LPCB LPS 1276 BS 9990
Capacity range10 – 5,000+ m³
Materials suppliedGRP · GFS · HDG · Coated · SS
Design life30+ years (steel)
Cold-climate ratingto −40 °C
GA drawing turnaround24 h
FOB lead time15–35 working days
20+Years manufacturing
1,500+Projects delivered
60+Countries served
5Material routes

What Is a Fire Water Storage Tank?

ZENTVO fire water tank — large bolted steel outdoor installation
Bolted steel fire reserve tank — outdoor installation

A fire water storage tank is the dedicated emergency water reserve that feeds sprinklers, hydrants, hose reels or fire pumps when public mains supply is insufficient or unreliable. It is the only component in the fire protection chain that is sized by code-mandated demand × duration, anchored to the building’s hazard classification — not by ordinary water demand.

Correct specification must satisfy NFPA 22, EN 12845, FM Global Data Sheet 3-2, LPCB LPS 1276, BS 9990, AS 2118.1 or NBC 2016 Part 4 — depending on the jurisdiction and insurance carrier.

The standard route matters because the same nominal tank can be accepted by one authority and rejected by another due to listing, refill time, suction geometry or cold-weather provisions. ZENTVO fixes the route before quotation so that material selection, effective volume and documentation match the approval path.

ZENTVO does not manufacture one material. We cross-compare GRP/FRP, glass-fused-to-steel, hot-dip galvanized, coated steel and stainless steel against your standard, water chemistry and site constraints — and recommend the material that actually passes approval.

ItemZENTVO specification
Governing standardsNFPA 22, NFPA 13, NFPA 14, NFPA 20, EN 12845, BS 9990, AS 2118.1, NBC 2016 Part 4, FM Global DS 3-2, LPCB LPS 1276
Capacity range10 m³ – 5,000+ m³ (single tank); larger via tank farm
Material optionsGRP/FRP sectional, glass-fused-to-steel, hot-dip galvanized, coated steel, 304 / 316 stainless
Approval routesFM Approved, LPCB-listed, WRAS for dual-use potable, UL where specified
Cold-weather provisionsNFPA 22 §16 — insulation + heating to maintain water ≥ 4.4 °C / 40 °F
Auto-refill rate (NFPA 22)36 h for fire-only; 8 h for combined fire + domestic
Anti-vortex pump suctionPer NFPA 20 §4.15 — submergence H ≥ 0.6 D + 0.4 m typical
Design life30+ years (steel); 25+ years (GRP/FRP)
Engineering turnaroundCAD/GA drawings within 24 hours of confirmed inputs
AuthorXu Alex, ZENTVO product documentation reviewer.
Technical reviewReviewed by Xu Alex, ZENTVO product documentation reviewer.
Last updatedJuly 1, 2026. Standard references and internal links checked before publishing.

Fire Water Tank Capacity — Worked Examples

The most common procurement mistake is buying nominal volume when the standard requires effective volume between low-level alarm and suction outlet. The worked examples below show minimum effective volume by hazard class, then explain where freeboard, hydrant demand and pump-suction submergence must be added.

Worked sizing formula: fire reserve = design density × design area × duration + additional hose / hydrant / standpipe demand + effective-volume allowances. EN 12845 OH3 example: 5.0 mm/min × 216 m² × 60 min = 64,800 L = 64.8 m³ before hydrant demand and freeboard. A quoted 70 m³ nominal tank may still fail if outlet elevation and low-water alarm leave less than 64.8 m³ effective volume.
EN 12845 — Hazard Class Density (mm/min) Area (m²) Duration Min. Effective Volume
LH (Light Hazard)2.2584 m²30 min5.7 m³
OH1 (Ordinary — Schools)5.072 m²60 min21.6 m³
OH2 (Ordinary — Office)5.0144 m²60 min43.2 m³
OH3 (Ordinary — Retail)5.0216 m²60 min64.8 m³
OH4 (Ordinary — Heavy Retail)5.0360 m²60 min108.0 m³
HHP1 (High Hazard Process)7.5260 m²90 min175.5 m³
HHP210.0260 m²90 min234.0 m³
HHP312.5260 m²90 min292.5 m³

Add hydrant and hose reel demand separately per EN 12845 §6.2. Add anti-vortex submergence + freeboard (+5 to +10%) on top.

Large fire water storage tank with geodesic dome roof
High-capacity fire reserve tank with aluminium geodesic dome

NFPA 13 (US, Canada, FM-aligned markets)

Sprinkler Hazard Density (gpm/ft²) Duration Approx. Volume
Light Hazard0.1030 min~17 m³
Ordinary Hazard 10.1560–90 min~51–77 m³
Ordinary Hazard 20.2060–90 min~68–102 m³
Extra Hazard 10.3090–120 min~255–340 m³
Extra Hazard 20.4090–120 min~340–455 m³

For NFPA 14 standpipe systems add 500 gpm for the first standpipe + 250 gpm each additional, capped at 1,000 gpm typical Class I, 30 min minimum duration.

BS 9990 (UK fire mains) Flow / Duration Minimum Volume
Wet rising mains1,500 L/min, 45 min minimum67.5 m³ for riser duty

What Counts as “Effective Volume”

⚠ Critical procurement warning

A 100 m³ nominal tank typically delivers only 85–90 m³ of effective fire reserve. Always quote your fire reserve as effective volume and require the supplier to confirm it on the GA drawing with the LWLA and outlet centreline dimensions.

Volume loss itemTypical allowanceStandard reference
Freeboard above overflow150 – 300 mmNFPA 22 §4.6
Volume above overflow → high-level alarm50 – 100 mmProject-specific
Volume between LWLA and suction outlet200 – 500 mm + anti-vortex submergenceNFPA 22 §4.6
Anti-vortex submergence above outlet centrelineH ≥ 0.6 × D + 0.4 m (D = suction DN)NFPA 20 §4.15
Sediment allowance below outlet100 – 150 mmNFPA 22 §4.6

Fire Tank Classification — Three Splits That Change the Spec

Pressure delivery

Gravity vs Suction Tank

  • Gravity — elevated, no fire pump, pressure by height
  • Suction — at-grade or basement, fed to fire pump (NFPA 20)
  • Selection: building height, available elevation, pump availability
  • Most common globally: at-grade suction tank + dedicated fire pump
Service type

Dedicated vs Combined

  • Dedicated fire — water reserved exclusively for fire
  • Combined fire + domestic — shared with potable reserve
  • Combined: NSF 61 / WRAS coating required; refill 8 h not 36 h
  • Combined requires insurer acceptance; NFPA 22 §4.2
Listing required?

FM Approved vs Code-Compliant

  • FM Approved — mandatory for FM-insured industrial & warehouse
  • NFPA 22 / EN 12845 compliant — sufficient for non-FM AHJs
  • LPCB LPS 1276 — UK third-party listing
  • Confirm with the insurance broker before tendering

Pump Suction Geometry — The Detail Most Tanks Get Wrong

NFPA 20 governs the fire pump, not the tank — but the tank suction outlet must respect pump-side geometry or the tank will fail factory acceptance. Without the anti-vortex plate and correct submergence, air entrainment cavitates the fire pump within seconds of fire-pump start.

Fire water tank suction outlet and anti-vortex plate detail

NFPA 20 §4.15 Suction Requirements

Key parameters ZENTVO verifies on every GA drawing before shipment

Suction outlet DN≥ 1.5 × pump suction nozzle DN
Outlet centreline above floor50 – 150 mm
Submergence above outlet (H)H ≥ 0.6 × D + 0.4 m
Anti-vortex plate diameter≥ 2 × D, centred over outlet
Anti-vortex plate height above outlet0.5 × D
Suction velocity at LWLA≤ 4.5 m/s (15 ft/s)
LWLA elevation≥ submergence H above outlet

Material Selection by Standard

Not every tank material is accepted by every fire code. This table is the single most useful filter at concept stage. ZENTVO supplies all five rows — see each product page for full specifications.

MaterialNFPA 22EN 12845FM Global DS 3-2LPCBCommon use
Bolted steel (HDG) NFPA 22 §6EN 12845 acceptedFM DS 3-2 approved variantsLPS 1276 Industrial, municipal, large-volume
Coated / welded steel NFPA 22 §6EN 12845 acceptedFM DS 3-2 approved variantsProject-specific Large dedicated fire tank
GRP / FRP sectional NFPA 22 §10EN 12845 with LPCB approvalFM case-by-caseLPS 1276 listed Building plant rooms, rooftops
Glass-fused-to-steel NFPA 22 §6EN 12845 acceptedFM DS 3-2 approved variantsLPS 1276 Industrial process plant, remote
316 Stainless steel NFPA 22 §6 routeEN 12845 acceptedFM project routeProject-specific Hospital, coastal, hygiene-critical
Concrete NFPA 22 §7EN 12845 civil routeFM project routeNot typical Civil works, very large reserves
ZENTVO galvanized bolted steel fire reserve tank
Hot-dip galvanized bolted steel — most common fire reserve format globally

Material Trade-Off at a Glance

MaterialCapacity fitCAPEX indexPlant room access
GRP/FRP sectional10–500 m³1.00×Excellent
HDG steel sectional50–1,500 m³0.85×Good (half-panels)
Glass-fused steel100–5,000 m³1.15×Limited
Coated welded steel500–5,000 m³0.95×Not feasible
316 Stainless10–500 m³1.80×Limited

Failure Modes Specific to Fire Water Tanks

Fire water tank construction and assembly quality control
Panel assembly and QC inspection at ZENTVO facility
Quality control process for fire tank components
Coating thickness and holiday test verification
Completed fire water storage tank installation
Commissioned fire reserve tank — handover inspection
💧

Pump cavitation at fire-pump start

Insufficient submergence / no anti-vortex plate

Prevention

H ≥ 0.6 D + 0.4 m submergence + anti-vortex plate per NFPA 20 §4.15

🔴

Stagnant water corrosion

Reserve sits months / years unused — no turnover

Prevention

GFS or 316 stainless interior; or coated steel + annual inspection per NFPA 25

❄️

Frozen tank in winter

No heating in dedicated fire tank in cold climate

Prevention

NFPA 22 §16 heating + insulation; verify lowest-recorded ambient; ZENTVO supplies to −40 °C

📐

Effective volume shortfall at acceptance test

Nominal volume quoted, not effective volume

Prevention

Document effective volume on GA drawing; supplier signs off LWLA / outlet centreline

⚠️

Insurer rejects tank at inspection

Material not FM Approved — discovered at delivery

Prevention

Confirm FM Approval requirement before PO; FM-insured sites only — ask the broker

🌊

Anchor failure in earthquake

No seismic design for anchor or shell

Prevention

NFPA 22 §14 / ASCE 7 / EN 1998 anchor design submitted with GA drawing

Typical Applications and Specification Path

Commercial Building Sprinkler Reserve

EN 12845 OH / NFPA 13 OH — GRP sectional (plant room), bolted HDG steel (basement)

20 – 200 m³

High-Rise Combined Sprinkler + Standpipe

NFPA 13 + 14, EN 12845 + BS 9990 — Bolted steel, GFS, or 316 stainless for combined potable

100 – 500 m³

Warehouse / Logistics

NFPA 13 EH, FM Global DS 8-9 — Bolted steel or welded steel, often FM Approved

200 – 1,500 m³

Industrial Process Plant

NFPA 22 + FM DS 3-2 — Glass-fused steel, welded coated steel

500 – 5,000 m³

Hotel / Hospital

NFPA / local code; combined fire + domestic — 316 stainless or WRAS-coated steel, NSF 61

50 – 300 m³

Remote / Oil & Gas Infrastructure

NFPA 22, API-related — GFS or welded coated steel; insulated for cold climate

500 – 5,000 m³

Fire Water Tank RFQ Checklist

Send these fourteen RFQ inputs to request a quote within 24 hours. The three highlighted items are the most decision-critical because they determine effective volume, approval route and pump-suction geometry before ZENTVO returns a draft GA drawing.

  • 1
    Required effective fire reserve volume (m³) — not nominal
  • 2
    Sprinkler hazard class (LH / OH1–4 / HHP1–4 / EH1–2) or raw demand × duration
  • 3
    Hydrant / standpipe / hose reel additional demand
  • 4
    Pump suction DN, NPSH-required, pump start sequence (NFPA 20 / EN 12845)
  • 5
    Governing standard (NFPA 22 / EN 12845 / BS 9990 / AS 2118 / NBC 2016 / local)
  • 6
    FM Approval / LPCB listing required? State Yes or No after insurer review; FM-insured warehouses normally require FM Approval.
  • 7
    Dedicated fire reserve, or combined with domestic / process?
  • 8
    Gravity tank (elevated) or suction tank (at-grade / basement)?
  • 9
    Site lowest-recorded ambient temperature (cold-weather sizing)
  • 10
    Seismic zone / design category
  • 11
    Site space envelope and access (door / lift / crane)
  • 12
    Indoor / outdoor / underground
  • 13
    Country of installation
  • 14
    Required FOB date

Frequently Asked Questions

How do I calculate the required fire water tank capacity?
Capacity = design density × design area × duration. Under EN 12845 OH3: 5 mm/min × 216 m² × 60 min = 64.8 m³ minimum effective volume. Under NFPA 13 OH2: 0.20 gpm/ft² × 1,500 ft² × 90 min ≈ 102 m³. Add hydrant, standpipe and hose reel demand separately, then add freeboard and anti-vortex submergence (+5–10%). The capacity section above shows the worked examples.
What is the difference between nominal and effective volume?
Nominal volume is geometric tank volume. Effective volume is the water actually available to the fire system — between the low-level alarm and the overflow, with anti-vortex submergence above the suction outlet per NFPA 20. A 100 m³ nominal tank typically delivers 85–90 m³ effective. Always specify effective volume in tenders, and require the supplier to confirm it on the GA drawing.
Which standard governs the tank itself?
NFPA 22 governs tank construction in North America and most NFPA-aligned markets (GCC, much of Asia). EN 12845 governs sprinkler-system water supply in Europe. BS 9990 governs UK fire mains. FM Global Data Sheet 3-2 applies to FM-insured properties and adds Approval requirements on top of NFPA 22. LPCB LPS 1276 is the UK third-party listing for fire tanks.
Do I need an FM Approved tank?
Only if the insured property is FM Global insured. FM-insured industrial, warehouse and data-centre clients almost always require FM Approved tanks. If FM Global is the insurer, specify FM Approved. If it is not an FM-insured property, NFPA 22 compliance without third-party listing is usually acceptable to the AHJ.
Can a fire water tank also store potable water?
Yes — a combined fire + domestic tank is permitted by NFPA 22 §4.2 when: (a) all wetted components carry NSF/ANSI 61 or WRAS BS 6920 certification, (b) the dedicated fire reserve sits permanently below the domestic draw-off, and (c) auto-refill is sized for 8 hours (vs 36 hours for fire-only). Insurers may impose additional conditions.
What is the minimum water temperature for a fire tank in a cold climate?
NFPA 22 §16 requires water be maintained ≥ 4.4 °C / 40 °F. Tanks in climates where ambient drops below 4 °C need insulation plus a heating system sized to recover from the design low temperature. ZENTVO has supplied tanks operating reliably at site lows of −40 °C.
What pump suction details does the tank need to support?
Outlet DN ≥ 1.5 × pump suction nozzle DN, centreline 50–150 mm above tank floor, with submergence H ≥ 0.6 D + 0.4 m above the LWLA and an anti-vortex plate ≥ 2 × D diameter at 0.5 × D height above the outlet. Without these, the fire pump cavitates within seconds of start.
What information is required to quote a fire water tank?
The fourteen-item RFQ list above. The three most critical inputs are (1) effective volume, (2) governing standard, and (3) FM Approval requirement. With these confirmed, ZENTVO returns a draft GA drawing within 24 hours and checks material route, pump suction, refill time and approval documents before pricing.

Sources & Technical Review

This page combines ZENTVO manufacturing documentation with public fire-protection, approval and potable-water references. Final compliance should be checked against the edition required by the engineer of record, insurer and local authority having jurisdiction.

  • NFPA 22 — water tanks for private fire protection.
  • BS EN 12845 — automatic sprinkler system design, installation and maintenance.
  • FM Global resources — FM-insured fire-protection design references, including property loss prevention data sheets.
  • LPCB LPS 1276 — approval standard for sectional tank systems used in fire protection.
  • NSF/ANSI/CAN 61 — drinking-water system components for combined fire + domestic tanks.

Ready to size and specify your fire reserve?

LPCB LPS 1276 · FM Global DS 3-2 · NFPA 22 · EN 12845 · ISO 9001 · ISO 14001 · BS EN ISO 1461. GA drawing and effective-volume confirmation within 24 hours of complete inputs.

Sizing the reserve?

Request the ZENTVO Fire Water Tank Capacity Calculator — EN 12845 / NFPA 13 worked sheet, free download.

Download Calculator
Comparing materials?

Request the Fire Tank Material Decision PDF — single-page filter by code, capacity range and approval requirement.

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Ready for quotation?

Send the 14-item RFQ list to info@zentvo.com. GA drawing and certifications package within 24 hours.

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GRP/FRP Fire Tank → Hot-Dip Galvanized → Coated Steel → Glass-Fused-to-Steel →

info@zentvo.com  ·  +86 153-1889-6990