Installation of Slimline Tanks

There are several factors that will determine the most appropriate location of your rainwater tank. First walk around your house and note the locations of your downpipes. The closer the tank is to a downpipe, the simpler your install will be.

Once you have selected an appropriate site, you can begin to prepare this site for the tank.

STEP 1: Check the relevant regulations relating to rainwater tank installation with your local council.

STEP 2: Your S-Line rainwater tank should be handled with care. When moving into position, avoid rough and sharp surfaces.

STEP 3: All SlimlineTanks must be installed on a level concrete slab (min 75mm) slightly wider than tank (100mm) length and width approximately 100mm if it allows.

STEP 4: Tank must have a minimum clearance of 50mm from walls or fence

STEP 5: All threaded fittings must be hand tight only using teflon tape. Be careful not to damage the thread if using a brass tap/ball valve

STEP 6: Water tank stands can be used but must be designed by a qualified consulting engineer.

Please refer to Australian Standards Handbook for installation instructions for further information HB 230-2006

Click here for brochure – Slim and round tanks under 6000



Prepare the ground for installation of your water tank – click here Steel tank preparation


Installing Your TankToggle
Dry System

In most cases, tank installations use PVC storm-water pipes to carry rainwater from the gutter to the tank inlet (see dry system diagram). Connecting the PVC pipe is hassle-free, and it should be glued with watertight cement. PVC pipes are inexpensive and neat and can be painted to match the colour of your home.  Alternatively high-density polyethylene (HDPE) pipe may be used.

The downpipe should be directed to run downwards and the rainwater should flow into the top of the tank. There should be enough fall in the pipe to allow gravity to drain water into the tank inlet.

A first flush water diverter and/or a rain head can be used to keep sediment and leaves out of the tank. Called a dry system, the pipes are allowed to dry out once rain stops.

Wet System

A wet system (see diagram), where water remains in the pipes after rain, connects one or more underground downpipes and carries water through an underground pipe to the tank. Wet systems rely on hydraulic head pressure to force water through sealed pipes and up into the tank inlet.

A wet system is useful for a larger roof catchment area, as the tank does not need to be located near the downpipe.  It is imperative to consider the height differential between the bottom of the gutter and the top of the tank. Allow at least 500mm differential. You can use our Ask an Expert service for more information about wet systems.

An important consideration is to use a filter before water enters the underground storm-water pipes. We recommend installing a first flush or a High-Flow Filter and/or Rain Head under the gutter. Inspection points should also be installed to allow a flush out, if required. Gutter guards are effective for keeping your wet system free flowing.



Installation Guide for Round Tanks

STEP 1: Line up all tanks starting with Tank 1 from your left;

STEP 2: Use Teflon tape on all directors (approximately 10 turns);

STEP 3: Screw directors (hand tied) to 1″ plastic fitting;

STEP 4: Fit hose supplied with S/S clamps;

STEP 5: Fit ball valve to 1″ brass outlet and on the other side fit plastic 3/4 plug;

STEP 6: We recommend that the overflow be installed on either: Tank 1: 9 o’clock; or Tank 4: 3 o’clock;

STEP 7: Silicone must be used in between overflow and tank. After screwing overflow to tank with six S/S grab screws use a hole saw to cut the hole between 50mm and 70mm;

STEP 8: We recommend that the After all tanks have been joined and overflow installed, slowly push them into position (Pro Plastics recommends 2 people when more than two tanks are placed into position).




Step 1:  Align the heights of the tanks overflows.  The lower or smaller tank will need to be raised so the overflows are at the identical same height, or try to purchase tanks that same height.  This will save some work.

Step 2:  Only one overflow is required if you have one downpipe. The other tanks do not have a drilled overflow.

Step 3:  Link the lowest outlets of each tank with a flexible hose.  Usually you should start with the inlet at the smallest tank in the chain of tanks but it doesn’t really matter as long as each tanks outlets are at the same height. 

Step 4:  The water will now align at the same height as water starts filling the tanks.  Connect your pump to the outlet on the last tank in the chain.