How to prepare a base for a water tank

Jas Naylor
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How to prepare a base for a water tank

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Project Overview

Before you can install a water tank, it’s important to have a strong enough base for it. We’ll show you how to build the retaining walls, using treated pine sleepers and galvanised posts, and how to make the base level using builders sand.  
Continue to Step-by-step instructions.

Step by Step Instructions

1 Cut timber for retaining walls for the base of the water tank
2 Install retaining walls for the base of the water tank
3 Make the base for the water tank
4 Position the water tank on the base
  • Step 1. Cut timber for retaining walls for the base of the water tank

    The best location for your tank is close to the downpipes coming off the roof. Once you have chosen your spot, measure out the footprint of the tank on the ground. Then cut treated pine sleepers to make retaining walls to surround that area. Remember to check with your local council for any regulations they may have for water tank locations.
  • Step 2. Install retaining walls for the base of the water tank

    To make the retaining wall for the base, join the sleepers together and use your mallet to hammer end posts into the ground at each corner. Then hammer star pickets into the ground next to the walls to reinforce them. Check all your sleepers are level then drive screws through the star pickets to secure the walls in place. For a larger base, you can make longer walls by connecting two sleepers together using a joiner post. 
  • Step 3. Make the base for the water tank

    Fill the base up to the top with builders sand and level it off. Now flatten the sand down with the plate compactor. Check the surface is even with your spirit level and compact extra soil where required. Once everything is level, unscrew and remove your star pickets. 
  • Step 4. Position the water tank on the base

    Place the water tank in position on the base. Then you’re ready for the plumber to connect it to your down pipe and storm water drain. If your area has heavy clay soil, instead of sand, the base will need to be made using a concrete slab with drain holes. 

Please make sure you use all equipment appropriately and safely when following the advice in these D.I.Y. videos. You need to be familiar with how to use equipment safely and follow the instructions which came with the equipment. If you are unsure, you may feel it is safest to consult an expert, such as the manufacturer or an expert Bunnings team member.

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