OaklandsPlastics

Most Oaklands Plastics tanks are manufactured for above ground use and aren't designed to withstand the ground and water table pressures of burial. If you need an underground installation, look for tanks specifically rated for below-ground use, which are built with thicker walls or ribbing to resist external loading. Always check the product spec before digging, as fitting an above-ground-only tank underground will void any guarantee.

These tanks are typically rotationally moulded from medium-density polyethylene (MDPE), a tough, UV-stabilised plastic that resists cracking, corrosion and algae growth better than metal or fibreglass alternatives. With correct installation and normal use, a polyethylene tank commonly gives 15–20 years of service, and being a single-piece moulding there are no seams to fail. They're also lightweight compared to GRP, making handling and installation more straightforward.

This depends on daily demand and available roof catchment area, but as a rough guide, a household using rainwater for toilet flushing and garden use typically needs 1,500–3,000 litres of storage. For livestock, irrigation or larger properties, capacities upward of 5,000 litres are common. It's worth sizing generously, as running dry during summer defeats the purpose of harvesting — our team can help you work out the right capacity from your roof size and intended use.

Most domestic water storage tanks don't require planning permission, particularly if sited discreetly and below any relevant height thresholds, but it's always worth checking with your local authority if the tank is large or highly visible. Building regulations become more relevant when the tank connects to plumbing systems, such as rainwater harvesting feeding into the house, where Part G and WRAS requirements on backflow prevention apply. Non-potable tanks must never be cross-connected to the mains supply without an approved air gap or backflow device.

Plastic tanks need a firm, flat, level base free of sharp stones — a compacted sub-base with a concrete slab or paving is the usual choice for larger tanks, while smaller ones can sit on well-compacted pea shingle. Any unevenness will stress the tank wall once it's full and heavy, so it's not something to skip on. As a guide, allow the base to extend slightly beyond the tank's footprint to support the full weight evenly.

Larger tanks are generally delivered on a kerbside pallet or crane-off lorry, and you'll need a suitable access route and enough people or equipment on-site to move the tank into its final position, as our drivers aren't able to carry tanks beyond the vehicle. It's worth confirming access width and any overhead restrictions at your delivery address in advance, particularly for rural or off-mains properties. Lead times vary by tank size, so check the product page or get in touch for current availability before planning your installation date.