Water Tank InstallationCorrect preparation is essential to ensure a long and trouble-free life for your water tank. Base Preparation Our poly tanks are very strong, but it is nonetheless important to have your tank standing on a flat level compacted base. This can be a concrete slab or crusher dust, but not sand. The base of your water tank must be fully supported at all times. Concrete Slab Concrete slabs must be at least 25 MPa and 100mm (4") thick with F62 mesh halfway through the mix. It should be screeded flat and level with no high or low spots. The finished surface should have a trowelled finish. Crusher Dust Crusher dust bases must be 300mm (12") wider than diameter of the water tank and prepared as follows: Remove at least 100mm (4") of natural earth, ensuring the base is flat and level. Refill with at least 75mm (3") of crusher dust thoroughly mixed with dry cement powder (for a 4m (13') base we suggest 2-3 bags of cement powder). Once spread, thoroughly compact the crusher dust with suitable compacting equipment, not by any other means. Thoroughly screed the surface and ensure the finished surface is perfectly FLAT AND LEVEL and free of stones, tree roots, etc. Do not water to set the cement powder, natural moisture will do this when your tank is in position. Burying Poly Rainwater Tanks (guide only) YOU MUST SEEK AN ENGINEERS ADVICE REGARDING YOUR PARTICULAR SITUATION. As a guide only we recommend that you do not bury your tank anymore than 1 metre into the ground. You must dig your hole 300mm (12") wider than the base diameter of your tank. If two tanks are to be buried side by side then separate holes must be dug. Prepare tank base as per our Base Preparation requirements above. Completely fill tank with water first, then backfill the hole with compacted crusher dust and cement powder. Compact 75-100mm (3-4") at a time. We also suggest that you erect a fence for safety reasons around the tank. Backfill Ratio = 3 parts crusher dust to 1 part cement powder. Plumbing Fittings You can choose an outlet and gate valve up to 32mm (1 1/4"). An overflow and strainer are supplied as a standard size for all tanks. If you need any extra fittings or gate valves please let us know when ordering. We will fit the strainer, overflow and brass outlet valve or tap to your tank at the factory. You can advise us of your preferred position for all these items by simply using our rainwater tank clock face diagram (PDF 18 KB). All other plumbing work is the responsibility of the purchaser. Note: The instructions here are a guide only. We advise that you seek an engineer's advice for your particular situation before attempting any of the above. Incorrect installation will result in voiding your tank warranty.