GRPFire Water Tanks

Capacity is normally dictated by your fire risk assessment, insurer's requirements, or the local fire authority — not guesswork. Many commercial sites work to a minimum of 45,000 litres for sprinkler backup, but sizing depends on hazard category, building size and hydrant availability. We'd always recommend confirming the required volume with your fire engineer or insurer before ordering.

Yes, many GRP fire water tanks are designed for underground installation, which keeps them out of sight and frees up surface land. They need to be rated for burial and installed on a suitable prepared base, usually with backfill instructions followed closely to avoid distortion of the tank walls. Above-ground installation is also an option where excavation isn't practical or ground conditions are poor.

GRP tanks need a level, well-compacted base — typically a concrete slab or compacted granular bed sized to the tank's footprint — to spread the load evenly and prevent settlement. For underground tanks, correct backfilling with the specified material is just as important as the base itself, as uneven pressure can distort the shell. Ground conditions vary site to site, so it's worth getting a groundworker to check suitability before delivery.

A combination unit houses the tank and fire pump set together as one factory-built package, which simplifies installation and reduces on-site pipework and commissioning time. It's a practical choice where space is tight or where you want a tested, pre-engineered system rather than specifying tank and pump separately. This can also make it easier to demonstrate compliance, as the unit is designed as a complete system from the outset.

If the tank is above ground, exposed, or sited somewhere prone to hard frosts, insulation is worth considering to stop the stored water freezing and becoming unavailable in an emergency. Insulated GRP fire water tanks use an insulated skin or lining to maintain water temperature through winter without the bulk of external lagging. Underground tanks benefit from natural ground insulation, so this is less of a concern below ground, though depth of cover still matters in very cold regions.

GRP tanks are low maintenance by design — the gel-coated finish resists algae build-up and is easy to wipe down or hose out during routine checks. Periodic inspection of fittings, access hatches, level indicators and any pump connections is still sensible to keep the system fire-ready. As the water is held in reserve rather than in constant use, most sites include the tank in scheduled fire system testing rather than treating it separately.