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How do you construct an above ground water tank?

Many horticultural companies use an above ground water tank in which to store water that is, among other things, used to irrigate crops. These above ground water tanks hold large volumes of water. In order to prevent cracking, tilting, corrosion and leakage, you have to construct the water tank correctly and precisely. This article shows you what the water tank construction procedure is.

Joshua Reijnen
Technical specialist Water engineering | December 12, 2020 | 5 min. reading time

Instruction video

Installing the pipeline

Determine the central point of the tank. Standard above ground water tanks have one drainage point at the center.
The open part of the pipeline has to protrude at least 300 mm above the foundation of the tank.
The lying part of the pipeline has to be at least 400 mm larger than the radius of the tank.
Make sure that the pipeline is stabilised, so that it cannot move during construction of the water tank. Also make sure that the pipeline does not leak.
The components for the suction hose and other pipelines under the water tank have to lie deep enough and protrude from the ground at approximately 1 meter from the above ground water tank wall. If there are several pipelines, then make sure that they are assembled at a distance of approximately 1 meter from each other (on account of gluing or blow-drying the corresponding tubes).

Laying the foundation of the above ground water tank

When you construct an above ground water tank, the base on which it is placed must be strong and flat. It is very important that the base is strong enough to comfortably support the weight of a full tank.
Create a ring of tiles along the diameter of the above ground water tank. Lay the tiles as tightly to each other as possible and make sure that they are absolutely level. Placing the tiles is the easiest in a layer of clean sand 5 - 10 cm thick. You can also opt for a concrete ring.
If the base for the tank consists of soil, then make sure that the soil contains no debris or sharp elements whatsoever, so that the floor of the above ground water tank cannot be damaged. You can also opt for the use of a ground sheet, depositing a layer of white sand on the base or having a concrete platform poured (of at least 250 mm thick and with a diameter that is at least 100 mm larger in circumference than the above ground water tank).

When you dig in the tank (which is what we recommend), then make sure that this is not done any deeper than 50 cm below the surface. The tank must at any rate be placed above ground water level. The diameter of the pit has to be approximately 1 metre wider than the diameter of the water tank (this will make further construction easier).

Assembling galvanised plates of the above ground water tank

Draw a circle that outlines where the walls will be.
Place the tank canvas and the wall covering at the center of the unassembled above ground water tank. Place them on a pallet or crate, so that they are not damaged and remain dry.
Assemble the bottom row of plates* and make sure that the bolts** are firmly tightened. The bolts should be attached in such a way that the bolt head is on the inside of the tank and the washer and nut on the outside.

Assemble the next row of plates in the same way. The plates have to be bonded, so that the vertical joints are staggered. Make sure that you tighten the previous ring each time you assemble a new ring. Spray the nuts and bolts with zinc compound after assembly.
Always assemble the corrugated plates of the next ring against the outside of the previous ring. This prevents leakage water from seeping in between the plates.

* Some water storage tanks with a diameter of 5.53 metres or more have to be constructed with corrugated plates that vary in thickness. If so, then the thickest plates should be assembled first. The bottom plate is coated.
** Above ground water storage tanks with a large diameter and height will, in addition to plates that vary in thickness, be supplied with different types of nuts and bolts (M10 x 20 and M12 x 25). The M12 x 25 bolts should only be used for the thickest plates, and only on the vertical joints.

Applying the above ground water tank wall covering

Roll out the wall covering in the tank, making sure that it remains as dry as possible.
Pull the wall covering 12-15 cm over the tank wall and secure it with the supplied plastic protection profiles. Place the covering on the floor, through the corners.
You can either cut off the surplus wall covering or assemble it as a second layer with the aid of the plastic protection profiles.

Fitting the above ground water tank canvas

Ask an expert to fit your tank canvas for you. Fitting a tank canvas is difficult and requires great precision. It should be left to an expert to avoid problems in the future.
Please note: Above ground water tank that are placed outside must be filled with 30-40 cm of water immediately after the tank canvas is fitted. This prevents the canvas from clattering in windy conditions.
If you have to use a ladder to work inside the tank after the tank canvas has been fitted, then always place the ladder in a strong plastic container to prevent damage to the canvas.
Never supplement the base of the above ground water tank with soil or sand if it is not filled with water.

Anti-algae cloth

Algae in the above ground water storage tanks can cause serious trouble. It is therefore important to prevent algae from forming. You can do this by covering the water tank with anti-algae cloth.

Permits

Before you construct above ground water storage tanks, check with your municipality whether you have a permit for its use. Not all municipalities grant such permission.

Maintaining the above ground water tank

The risk of damage caused by breakage or flooding of a water tank increases every year. Among the most common causes of breakage are tilting, corrosion and leakage. You can limit the risk of breakage by having the tank inspected regularly, by putting maintenance measures in place and by having it cleaned and certified in time.

How do you construct an above ground water tank?

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Joshua Reijnen Product specialist Water technology