This brief guide will help to show you how to connect a water tank.  See the page on Rainwater Harvesting to see how to select the right size tank for your home.

Generally, most water tank installations involve using PVC stormwater pipe to direct rainwater from the gutter to the inlet of the tank, as shown in the "Dry System" image above. The PCV pipe is quick and easy to connect, and is glued with a water tight cement. PVC is inexpensive and neat, and can be painted to match other downpipes or the wall of your home.

Other alternatives to PVC include using rolled metal downpipes, and high density polyethylene (HDPE) pipe. 
The simplest way to connect the downpipe to the top of the tank is to run the pipe directly, allowing some fall in the pipe so the water flows by gravity to the tank inlet.  You can install a first flush water diverter and / or a rain head to help keep sediment and leaves out of the tank.  This is called a dry system, as the pipes are allowed to dry out once the rain has stopped.

An alternative system connects one or more downpipes underground and runs the water in an underground pipe to the tank location, as shown in the "Wet System" image. This system relies on hydraulic head pressure to force the water through the sealed pipes and up into the tank inlet. This is termed a wet system, as the water stays in the pipes after the rain has stopped.

Using a wet system allows you to capture water from a larger roof area, as tank does not need to be near each downpipe.  It is important to consider the height differential between the bottom of the gutter and the top of the tank, and allow at least 500mm differential.  contact ask an expert for more information on designing wet systems.

When installing a wet system, it is important to consider filtering the water before it enters the underground stormwater pipes. This is usually done with a first flush and / or rain head installed under the gutter. Inspection points should also be installed in the system to allow it to be flushed out if required. Gutter guard may also be effective at keeping your wet system flowing freely.

The "Transfer System" is a more complex solution that allows you to position your water tank in a more convenient location, without having to rely on gravity to carry the water to the water tank.  This system uses a sump pump to transfer the water to the storage tank.