How to install a large Polyethylene water storage tank

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  • OVERALL DIFFICULTY INDEX: 3/10
  • IF YOU HAVE NO TOOLS, YOU PAY $35 TO GET THEM FOR THIS JOB
  • IF YOU HAVE NO EXPERIENCE YOU SPEND 4 HOURS TO CARRY OUT THIS JOB
  • NO SAFETY ISSUES
BEFORE YOU START​
  • 15" plumber wrenches are needed if the tank has a large bottom drain i.e. 1.5 or 2 inches. This depends on the tank's capacity (6000 L pictured here).
DISCLAIMER:
Our pictorials are of informative nature and do illustrate works carried out by ourselves at our own premises for our own use and satisfaction.
Readers who envisage to carry out similar works inspired by the below method shall do this at their own risks and liability.

Choosing the location of the water tank in the backyard

Keep in mind that you won't be able to move the tank once full of water, so better to chose well its location!
This includes making sure that:
  • You can circulate around it,
  • Easily connect the piping or hoses without interfering with passages or surroundings,
  • The intended water tank place is somehow level.

Making the ground level underneath the tank

Just dig the high side, add soil on the other and then comb the tank footprint to make sure it is level.
When combing, you need to remove all large and medium stones as these can later puncture your PE Tank.

Installing the main water tank valve

Check the water outlet and buy a ball valve of the same size.
​Do not use a reducer to install a smaller valve.
Depending on tank's capacity, the size ranges from 1 to 2".
Most common valve size for 6,000 and 10,000L tanks is 1 1/2".
If you're buying it online, make sure of the thread type of the  valve which is NPT for the US and BSPT for the rest of the world.
Clean the thread with a metal brush to remove any particles.
Apply Teflon tape on both sides of the union that will be used to connect the ball valve to the tank.
Teflon is wrapped clockwise until the thread vanishes.
​Try to make it conical i.e. thicker inside and thinner at the edge. 
Start assembling the union to the valve, then use one or two large plumber wrenches to assemble both to the tank.
If required, dig a small hole below the water valve's handle so you can rotate the valve:

First water tank fill for testing

Fill first with a little water (around 1/4 of the tank capacity) to test and then to the top. 

Fitting the float valve and water supply to the water tank

A float valve is now needed to complete the installation.
If needed, use a file to enlarge the available hole until the valve's thread goes through.
Introduce the valve and push it out until its thread crosses the tank's wall.
​Fit the nut and tighten using a smaller wrench or monkey pliers.
Make sure you do not rotate the float valve while tightening. It should remain vertical as shown here.
You still need to connect your water supply pipe and that's it!​

See also our other tutorials on backyard and gardening works...

...and buy your main tank valve and float valve from our partners, pay attention to the thread type!