Under-house water storage

This is a rainwater tank system installed under your house.

If you have the room, this solution offers the visual advantage of concealment.

There are many "bladder" suppliers. Look out for those that offer some or all of the below features:-

• Use of all of roof catchment
• Frame and groundsheet protected
• Come with all connections
• Permit bladder-linking to increase capacity
• Good fittings (preferably compression couplings)
• Effective overflow handling that does not stress the system
• Eligible for grants and rebates
• Look for a 10-year warranty

Slim-line Tanks

Probably a majority of homes in urban areas would not have the area for a conventional round tank. 

Slim-lines that come in a huge variety of shapes and configurations are then a possible solution.

You may need to pair a couple to get enough capacity and qualify for any rebates (depending on the requirement).

Conventional steel/concrete/fibreglass

Metal Tanks are made from corrugated or flat rolled metal and can be galvanised or colorbond. The steel tanks have an extra coating called Aquaplate which will increase the life of the tank and protect the water quality.

Visit www.bluescopewater.com.au website for warranty guidlines associated with metal tanks.

Concrete tanks can be bought ready-made or custom-made on-site.

Fibreglass tanks tend to be more expensive: they’re rust and chemical-resistant and designed to withstand extreme temperatures. They’re more suitable for above-ground installation.

What are polyethylene water tanks?

HDPE (High Density Polyethelene) tanks are constructed through a process called roto moulding. The process consists of melting raw material inside a sealed hollow mould. This mould is then rotated for a calculated period around two perpendicular axis so as to distribute the melted material in the desired fashion. The heat is turned off while the mould continues to rotate. When cool enough the product is released from the mould, and the process starts again for the next product. Different rotating patterns achieve variations in such things as wall thickness as required. 
The material is sturdy and resists vigorous handling, stabilised against ultraviolet light, is resistant to both hot and cold extremes and is used in the mining, oil/gas, agriculture, marine, chemical storage and food industries.

Items can be custom manufactured to suit any application.

The round examples in the picture will suit larger urban blocks with room for pads and confer the extra advantage of better water capacity and rebates (from Council).

We recommend and use proven poly tank makers such as Rapidplas for round tanks and Clarke tanks for Poly slimlines. 

Water-saving devices/accessories

There are many accessories that go with and improve the action of rainwater tanks.

Following is a small selection of the most essential...

Leaf diverter

Even if you haven't got a tank, these are an excellent protection against blocked downpipes. Blocked downpipes cause gutter overflow and are a headache to clear.

If you do have a tank, then clear downpipes and zero build-up at the tank inlet will ensure best use of your catchment.

First-flush device

This device diverts the first flush of water from the roof to a long holding pipe with a slow-release valve at the bottom connected to a hose.

The first flush contains dust, organic contaminants, tannin, heavy metals, chemical residues etc. that reduce the quality of your stored water especially if this is plumbed internally to outlets such as toilets. etc.

First flush diversion also reduces tank maintenance and is recommended by leading pump manufacturers such as Davey to prevent sediments and other debris from wearing down the pump seal or getting caught in the pump impeller.

Minimal capacity for a diverter pipe would be ca. 20 litres.

Once the pipe is full, a floating ball and a seat seal off further diversion. The pipe then drains slowly ready for the next use.

Water diverters

In this example, water collects in a reservoir and can be distributed via 4 12mm and 1 18mm hose connections.

(picture to right)

Any excess water goes to a tank or stormwater drain.

http://www.australianrainsaver.com.au/how-it-works.html 

Another approach called the "Lenny" uses a flap for you to control zero or 100% diversion.

http://www.waterdiverters.com.au/

A simple approach is an automatic diversion to a single outlet adaptable to 18mm gauge.

http://www.water-diverter.com.au/

Rain filter

If your rainwater is going to be used internally for toilets and washing or whole of house supply, it is essential to apply "pre-treatment" as described above (first flush diversion, etc.) but also to place a filter between the pump and the house inlet.

The filter (picture to right) is a "triple-action system" filtering fine sediments down to 15 micron protecting internal appliances. 

It will also block odours and colours protecting against the tainting of laundry and toilet bowls.

http://www.rainharvesting.com.au/rain_filters.asp