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1. Above-Ground Tanks

  • Standard Polyethylene (PE) Tanks: Lightweight, robust, and cost-effective. Ideal for garden irrigation, retrofits, and small commercial or farming use. Available in cylindrical or space-saving "slimline" vertical/flat shapes (400L to 30,000L+ by linking). Note: Uninsulated; requires winter draining/pump removal if used for irrigation.

  • Insulated GRP (Glass Reinforced Plastic) Tanks: Feature up to 50mm "sandwich" insulation for internal or external use.

    • One-Piece: Available in various sizes from 30L up to 9,000L.

    • Sectional: Built to almost any capacity or shape. Ideal for outdoor scale or restricted indoor access (e.g., loft hatches). Includes specialist installation.


2. Below-Ground Rainwater Tanks

Tough, lightweight, British-made one-piece GRP tanks (manufactured to BS 4994) featuring a 10-year warranty. They can be installed with concrete backfill (or granular backfill for heavy-duty versions) and support traffic with a cover slab. All GRP models come pre-fitted with a stainless steel calmed inlet and an overflow trap with a built-in backflow prevention device to comply with BS 8515.

  • Low-Profile Plastic Tanks: Available in a limited range of sizes.

  • RainSava® Domestic GRP: Capacities from 1,500L to 7,500L.

  • Commercial & Large-Scale GRP: * Standard: 10,000L to 38,000L.

    • RainTech® Pro: 40,000L to 90,000L.

    • RainTech® FT: Integrates a self-cleaning HYDRAPRO® FT filter unit into the access shaft, minimizing invert drop to just 80mm. Available across all RainTech sizes.


3. Header & Break Tanks (Internal Use)

Designed to bridge the gap between main underground storage and building outlets, utilizing dual inlets for both pumped rainwater and mains water backup.

  • Header Tanks: Placed at a high level to gravity-feed lower outlets (e.g., WCs). Pressure scales at 1 bar per 10m of height. * Domestic Model: A compact, unpowered 18L dual-inlet tank with a screened weir overflow and drip tray.

  • Break Tanks: Positioned at ground or basement level, feeding water to a booster pump set to achieve the required system pressure in larger buildings.

Commercial Water Tank Overview


Rainharvesting Systems offer a comprehensive range of rainwater, header, and break tanks designed for domestic, agricultural, and commercial use. Options include above-ground, below-ground, and interior installations in various materials and capacities.