4 Août 2026

APSAD Fire Water Storage Tanks: How to Size Them According to APSAD R1

Clarification note: The acronyms and referentials cited in this article (APSAD, CNPP, D9, SDIS, ERP, LH/OH/HH classes, etc.) belong to the French fire protection regulatory framework. This content can serve as a general reference guide if the installation is located in France or if French standards are being used as a benchmark, but fire safety regulations vary by country and region. Before applying any of these criteria outside of France, it is essential to check the local regulations in force in the relevant territory.

An undersized fire water storage system exposes the operator to regulatory non‑compliance and loss of insurance coverage. The APSAD R1 standard defines the sizing rules for sprinkler fire protection systems. Here is what you need to correctly size your fire water tank and select solutions that comply with current standards.

Key Takeaways

The tank is sized according to the APSAD R1 standard issued by CNPP
Tank capacity depends on the risk classification and required flow (D9 methodology)
It provides the primary water supply for the sprinkler system during a fire
APSAD compliance conditions insurance coverage
A certified expert must validate sizing and installation
The fire water tank must undergo mandatory periodic inspections: network checks, pump inspection, and compliance reporting

Understanding the Standard

Before sizing a fire water storage system, it is essential to understand the regulatory framework. The D9 practical guide provides the methodology for calculating water requirements.

Objectives of the Regulation

APSAD R1 is a set of technical requirements issued by CNPP, It defines the design, installation, and maintenance of automatic sprinkler systems.

This standard governs sprinkler installations and ensures a reliable hydraulic supply under constant pressure. Compliance is required by nearly all insurers, making it a guarantee of quality and certification for operators.

Scope of Application

The regulation applies to any building equipped with a sprinkler network: logistics warehouses, industrial sites, retail stores, and public‑access buildings (ERP).
A fire water tank is required when the public network cannot guarantee the required flow for the entire extinguishing duration.
High-hazard facilities—especially those storing gas or flammable products—are particularly concerned.

How to Calculate the Volume of a Fire Water Tank

APSAD R1 classifies buildings by fire risk level to determine sprinkler network characteristics and the required water reserve volume.

Risk Class	Building Type	Typical Minimum Tank Capacity
Light Hazard (LH)	Offices, light retail	100–200 m³
Ordinary Hazard (OH)	Warehouses, light industry	200–500 m³
High Hazard (HH)	Heavy industry, hazardous storage	500 m³+

The higher the risk level, the greater the water demand, sprinkler flow, and tank capacity. Final classification is determined through a risk assessment conducted by a certified engineering firm, which sets the safety objectives for each site.

Why This Classification Matters

Risk class directly influences:

Fire water tank volume
Required sprinkler flow
Required water supply duration
Tank selection and corrosion‑protection level

For example:

A logistics warehouse classified OH typically requires a galvanized steel tank, and a chemical or petrochemical site classified HH may require a dedicated internal coating to ensure long‑term durability.

APRO Industrie offers two protection levels (galvanized or internal coating), allowing both OH and HH configurations to be addressed with a modular solution.

Required Flow

The system must guarantee a constant nominal flow for 60 to 90 minutes, depending on risk class. Pump outlet pressure must remain stable and precisely adjusted throughout the fire event to ensure sprinkler efficiency. These parameters are part of the overall system calculation.

Technical Parameters to Consider

Beyond volume, tank placement and material selection directly impact compliance.

Tank Placement

Underground solutions suit urban areas with limited footprint
Above‑ground tanks are easier to inspect and maintain
In all cases, the tank must remain accessible at all times to fire and rescue services, in accordance with fire safety regulations

Materials for Fire Water Tanks

Solution	Installation Time	Civil Works	Modularity	SDIS / APSAD Compliance	Operational Summary
Bolted steel tank	Very short (300 m³ installed in a few days)	Low (simple slab)	Very high	Excellent (customizable capacity)	Most flexible solution: fast, scalable, ideal for active sites or constrained environments
Concrete tank	Long (weeks to months)	High (excavation + formwork)	Low	Good but fixed	Robust but rigid, poorly suited to evolving risk
Flexible tank	Very short	None	Medium	Medium to limited	Temporary or backup solution, sensitive to operating conditions
Open basin	Long	Very high	High volume but not modular	Variable (risk‑based)	Large capacity but large footprint and low operational control

For industrial fire water storage systems, bolted steel tanks remain the preferred solution for large‑capacity sites. APRO Industrie designs bolted sprinkler tanks that ensure permanent, easily accessible water supply for automatic extinguishing systems, hose reels, and other fire fighting equipment.

Compliance Requirements

A compliant APSAD tank must undergo regular inspections to remain fully operational.

Mandatory Inspections

APSAD compliance requires periodic inspections by an accredited body:

Available volume
Hydraulic network condition
Pump operation
Control equipment
Outlet pressure

Each inspection results in a verification report provided to the operator and insurer. A non‑inspected system may lead to suspension of fire insurance coverage.

Technical Documentation

Successful fire water storage projects rely on:

Full understanding of regulatory requirements
Technical constraints of the site
Insurer expectations

Since 1987, APRO Industrie has supported industrial clients with turnkey solutions covering the entire project: APSAD R1 sizing study, risk analysis, tank design and manufacturing, transport, on‑site assembly, commissioning, and preparation of technical documentation for insurers and control bodies.

APRO Industrie acts as a single point of contact throughout the project, streamlining project coordination, reducing lead times, and securing regulatory compliance.

DISCOVER OUR APSAD-CERTIFIED SPRINKLER TANKS

Sizing Fire Water Reserves in Industry

Requirements vary by sector. Here are the two most common configurations:

Logistics Sites (OH)

A logistics warehouse typically falls under OH classification. The sprinkler network often covers several thousand square meters. The fire water tank must ensure at least 60 minutes of water supply duration, with an independent backup pump and appropriate verification systems.

Heavy Industry (HH)

HH sites require the largest volumes, the dedicated reserve may exceed 1,000 m³. Private fire-protection infrastructure is generally financed and maintained by the operator.

Why work with an expert?

Sizing a fire protection system is a technical and regulatory process requiring specialized expertise.

Technical Support

A certified APSAD fire protection expert performs the sizing study, selects the appropriate tank, and produces the complete technical file—essential for proper installation and certification.

Since 1987, APRO Industrie has supported clients in designing installations compliant with regulatory requirements, working with qualified and recognized installers.

FAQ - APSAD Fire Water Tank

What capacity is required under R1?

From 100 m³ for light hazard to over 500 m³ for high hazard. Exact calculation is performed by a certified engineering firm as part of the site’s safety study.

Is this type of tank mandatory?

Yes, whenever the building has a sprinkler network and the public network cannot guarantee the required flow. Industrial insurers require it to maintain fire insurance coverage.

How is a sprinkler reserve sized?

Based on risk class, involved surface area, nominal flow, and extinguishing duration.

What is the difference between an open basin and a fire water storage tank?

A basin is an open structure for very large volumes, meanwhile a tank is a closed, compact, easier‑to‑maintain solution. Both can meet fire water tank requirements.

Who can install an APSAD‑compliant tank?

A qualified professional capable of producing the technical file and ensuring compliance. APRO Industrie manages fire protection projects from design to commissioning.