Industrial Rainwater Harvesting: Storage and Regulatory Requirements

64% of Metropolitan France was affected by water-use restrictions during drought periods in 2023 due to surface water shortages. Source: French Ministry for Ecological Transition, 2023.

2.7 Billion m³ of Water Per Year is withdrawn for industrial and commercial activities in France, with industry accounting for the largest share. Source: SDES – Statistical Data and Studies Department, Ministry for Ecological Transition

+6.2% CAGR (2026–2035) Estimated annual growth of the global rainwater harvesting market. Source: OMR Global Market Research, 2025.

As water resources become increasingly constrained and water costs continue to rise, rainwater harvesting is becoming a strategic investment for industrial and commercial facilities.

Collecting and reusing rainwater helps businesses reduce operating costs, improve environmental performance, and enhance resilience to water supply disruptions.

Modern rainwater harvesting systems rely on storage tanks, reservoirs, and collection infrastructure specifically designed for industrial buildings and production facilities. Today, manufacturers offer a wide range of solutions tailored to industrial and commercial applications.

But which storage solution is the right choice, and what regulatory requirements should businesses consider?

Key Takeaways

• Rainwater harvesting reduces water costs and environmental impact.
• Collected rainwater is generally intended for non-potable applications such as cleaning, sanitation, irrigation, and industrial processes.
• Regulatory requirements vary by country and may include permits, declarations, and monitoring obligations.
• The choice of storage tank depends on required capacity, roof catchment area, and site constraints.
• For large storage volumes, above-ground bolted steel tanks provide one of the most flexible and durable solutions.
• Pumps, filtration systems, and monitoring equipment ensure water quality and reliable distribution.

Why Rainwater Harvesting Matters for Businesses

Rainwater harvesting delivers both economic and environmental benefits.

By replacing municipal or utility-supplied water with harvested rainwater for suitable applications, businesses can significantly reduce water consumption costs while improving resource efficiency.

A well-designed system also helps organizations meet sustainability objectives and strengthen water security in regions facing increasing water stress.

Proper system design requires careful consideration of storage capacity, water treatment requirements, and intended end uses.

Typical Industrial Applications for Harvested Rainwater

Collected rainwater can be used for a wide range of non-potable applications, including:

• Cleaning floors, vehicles, and industrial equipment
• Toilet flushing and sanitary systems
• Industrial process water applications
• Cooling systems and closed-loop circuits
• Irrigation and landscape maintenance
• Fire protection water reserves

Landscape irrigation and grounds maintenance are among the most common applications in commercial and industrial environments. These uses typically require dedicated pumping and filtration systems to ensure reliable operation.

Storage Solutions for Industrial Rainwater Harvesting

Not all storage systems offer the same performance, flexibility, or long-term value.

How to Choose the Right Storage Solution

The selection of a storage system depends on several factors:

• Required storage volume
• Available installation space
• Site accessibility
• Water quality requirements
• Budget and lifecycle costs

Available technologies include tanks, cisterns, and reservoirs designed to meet specific industrial requirements.

Comparison of Main Storage Solutions

Storage Solution	Typical Capacity	Advantages	Best Applications
Above-Ground Polyethylene Tank	Up to 100 m³	Low cost, quick installation	Small facilities, temporary storage
Underground Concrete Tank	Up to 100,000 m³	Long lifespan, thermal stability	Permanent facilities with major civil works
Bolted Steel Tank (APRO Industrie)	Up to 10,000 m³	Modular, large capacity, long service life, factory-coated, relocatable	Industrial production sites, urban facilities, long-term investments
Flexible Bladder Tank	Up to 1,000 m³	Portable and flexible	Temporary installations
HDPE Tank	Up to 100 m³	Lightweight and economical	Commercial facilities and supplementary storage

Why Bolted Steel Tanks Are Ideal for Large Storage Capacities?

For industrial projects requiring more than 10,000 liters of storage capacity, bolted steel tanks offer significant advantages in terms of logistics, durability, and adaptability.

Since 1987, APRO Industrie has specialized in the design, manufacture, and installation of industrial storage tanks for demanding applications worldwide.

Bolted steel tanks provide several practical benefits:

• Factory-manufactured panels allow tank capacities of up to 1,500 m³ to be transported on a standard truck, reducing transportation requirements and project carbon footprint.
• Compact delivery dimensions simplify installation on urban and constrained sites.
• Tanks can be dismantled, relocated, expanded, or reconfigured as operational requirements evolve.
• The ability to relocate the asset protects the long-term value of the investment.

Coatings and Materials

The choice of internal lining is critical and depends on both the water quality and the intended use.

• Galvanized Steel + Standard Liner: Suitable for collecting rooftop runoff from non-polluted surfaces for irrigation, sanitation, and general utility water applications.
• Epoxy-Coated or Glass-Fused-to-Steel Tanks: Recommended when runoff originates from areas exposed to contaminants, chemicals, or industrial activities that may produce aggressive leachates. These coating systems provide enhanced resistance to corrosion and chemical attack.

Unlike many manufacturers that offer only standard galvanized solutions, APRO Industrie provides a full range of coating technologies tailored to specific operating environments. All coatings are factory-applied before delivery, eliminating on-site treatment operations and ensuring consistent quality and watertight performance.

For industrial sites handling potentially contaminated runoff, APRO Industrie can also integrate pre-treatment platforms equipped with filtration systems or rotary screens upstream of the storage tank.

Regulatory Considerations

Rainwater harvesting systems are subject to regulatory requirements that vary significantly by country and region.

Businesses should verify all applicable local regulations before implementing a rainwater collection system.

Standards and Compliance Requirements

Depending on the jurisdiction, requirements may include:

• Permits or declarations to local authorities
• Environmental approvals
• Water quality monitoring
• Metering and reporting obligations
• Compliance with plumbing and building standards

Where harvested rainwater is connected to wastewater systems, additional reporting and metering requirements may apply.

Definition: Public Wastewater Infrastructure: Public wastewater infrastructure refers to the municipal network that collects wastewater and transports it to treatment facilities. In many jurisdictions, rainwater reuse systems connected to public wastewater networks must be declared to the relevant authorities and may require flow measurement for wastewater charging purposes.

Technical Requirements

Beyond administrative requirements, rainwater harvesting systems should comply with technical best practices to ensure water quality and user safety.

Typical treatment stages include: Gutter pre-filtration, fine sediment filtration, optional UV disinfection, storage and distribution systems. A complete separation between potable water and non-potable water networks is essential and often required by law. Clear identification of non-potable water outlets and regular maintenance records are also recommended industry practices.

Implementing an Industrial Rainwater Harvesting System

A successful project typically follows these key stages:

• Assessment of water demand and roof catchment areas
• Calculation of recoverable water volume based on rainfall data and runoff coefficients
• Completion of any required administrative procedures and permits
• Selection and installation of collection, filtration, storage, and monitoring equipment.
• Commissioning, testing, and ongoing maintenance.

APRO Industrie supports clients throughout the entire process, from feasibility studies and system sizing to installation, commissioning, and long-term operational support.

 

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Frequently Asked Questions

What regulations apply to industrial rainwater harvesting?

Requirements vary by country and local jurisdiction. Depending on the application, permits, declarations, plumbing standards, environmental regulations, and monitoring obligations may apply.

How is the required storage volume determined?

Storage capacity depends on roof catchment area, local rainfall levels, water demand, and system efficiency. For example, a 1,000 m² roof receiving 700 mm of annual rainfall can potentially collect more than 600 m³ of water per year. A professional engineering assessment is recommended to optimize system sizing.

What can harvested rainwater be used for?

Typical uses include: Equipment cleaning, toilet flushing, irrigation, industrial processes, cooling systems and fire protection reserves. Applications requiring potable water quality generally require additional treatment and must comply with local drinking water regulations.

Which standards apply to rainwater harvesting systems?

Applicable standards vary by region. However, all systems should ensure complete separation between potable and non-potable water networks and incorporate appropriate treatment and monitoring equipment.

Which storage tanks are typically used for industrial rainwater harvesting?

For large-capacity installations, bolted steel tanks are often the preferred solution due to their modular design, factory-applied protective coatings, long service life, and ability to be relocated if site requirements change.

Optimize your rainwater management strategy, improve water resilience, reduce operating costs and support sustainability goals with APRO Industrie's industrial storage solutions. Identify the ideal solution for your rainwater harvesting project.

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