Galvanised steel tanks in Sheffield

Storage above the old foundations

Digging on Sheffield's industrial land means meeting old footings, slag and buried services, and digging on its hillsides means fighting the slope. Keeping the store above ground sidesteps most of that, because nothing below the slab needs to be opened up.

Panels can be unbolted and moved later, which suits a business that leases its premises or expects to expand. The steel is galvanised against the weather, and the water itself sits in a separate liner, so the shell never has to be watertight on its own.

Who stores water this way here

Manufacturers and engineering firms in the Don valley and around the Advanced Manufacturing Park hold process or recycled water. Bus, haulage and plant depots want wash-down water on tap. Sports grounds, nurseries and farms on the western fringe store irrigation water, and large roofs make rainwater harvesting at scale realistic in a city with Pennine rainfall.

Capacities run from tens of cubic metres for a depot to thousands for a big irrigation store, and the same panel system covers the range.

Slab, shell, liner, fittings

Others build the concrete or engineered pad. A tank can't stand straighter than the slab beneath it, so we put a level across it and confirm the setting-out before lifting the first panel. Then the build follows a set order.

• Galvanised panels bolted course upon course to the height on the drawing
• A made-to-measure liner hung inside, taking all of the water pressure
• Inlet, outlet, overflow and a level gauge fitted and made watertight
• Water let in a stage at a time while we watch the tank and fittings

Getting panels onto a tight site

The panels arrive stacked flat and each one can be moved by a small crew, which makes a yard behind a narrow gate or a cramped works site perfectly workable. We agree access and a laydown area before the build so the job doesn't stall in the street.

Commissioning is the final step. The tank is brought up to full in stages, every joint and connection is watched as the load rises, and only then does it go into service.

Where the tank should stand

Before the order goes in, we talk through size and position: where the tank can sit relative to the downpipes or the process line, how much height the inlet needs, and how the panels will reach the spot. The volume itself comes from your own water-use figures or your engineer's. A depot washing a fleet every night needs a very different store from a sports ground topping up through August.