Ensure that the roof surface is suitable for collecting quality rainwater
Colorbond® and Zincalume® steel sheets, well fired glazed tiles, concrete/cement tiles, clay tiles and composite tiles are popular choices for rainwater collection.
If water is intended for drinking-:
(a) contact the manufacturer to confirm whether the roofing material is suitable for potable water collection, and obtain a certificate of classification,
(b) ensure all pipes and fittings used within the system are also approved, and
(c) check local Council requirements.
Some roof surfaces are good for collecting rainwater and some are dangerous. If you are about to build a home, make an informed decision about the roofing material to use. If you intend to use an existing roof, check to see if the material is suitable.
The most suitable roofing materials for collecting potable water* are:
1. Colorbond® steel sheets or tiles
2. Zincalume® steel sheets or tiles
3. Glazed tiles well fired
4. Concrete/cement tiles
5. Clay tiles
6. ** Fibro - new type only
7. Composite tiles - bitumen based
[* Potable water is water fit for human consumption - safe drinking water.]
** Fibro, which is sometimes referred to as Super Six, that was originally made from a mix of asbestos and other materials such as bitumen based roofing products are not recommended for potable water catchment, however there are some companies that have approved sealants and paints for these types of roofs. The manufacturers of these products claim that a fibro roof, if it is treated correctly with their products, is quite safe to collect potable water from.
We have not listed aluminium, copper, galvanised steel or stainless steel or other types such as clear roofing because these are not the every day popular total roofing materials. Colorbond® and Zincalume® are BlueScope Steel Ltd trademark brands and these names have become everyday names to describe pre-painted zinc and aluminium coated steel which is manufactured and marketed throughout the world. Similar products to BlueScope are manufactured around the world by a variety of companies and marketed under several brand names. Most come with substantial guarantees to cover installation in certain climatic zones.
Colorbond® steel roofing material comes in a special grade approved for potable water. Zincalume® has a coating consisting mainly of zinc and aluminium hence its name, but it does not come in a grade approved for potable water. That does not necessarily mean that it is unsafe to collect potable/drinking water from the roof. What it does say though is that it is not "category" approved.
Cement and clay tile roofs can create some difficulties when it comes to collecting potable water. There are a lot of various minerals in the clay and cement used for making tiles and there is no guarantee the clay pit was not contaminated. The temperature tiles are usually fired at is not sufficient to fuse all minerals together to prevent them from leeching, thus it could never be guaranteed that a cement or clay tile roof would be as safe as some other types of roofing material. Tank cleaning companies will tell you that if the roof tiles are red or green, the sludge in the bottom of the tank will be red or green. To make a red or green tile requires various oxides to be applied to the tile prior to firing and this is proof enough to me that the temperatures some tiles are fired to is not sufficient enough to stop the oxides from eventually ending up in the tank. To be sure about tile roofs consult with the manufacturer to see if the coatings used are harmless. For tile roofs there are companies that will clean the roof down, seal it with an approved sealer and apply a decorative coating that is approved for potable water, but make sure the certificate for the coating is genuine.
If the water that is being collected from the roof types above is not being used for human or animal consumption the material the roof is made from is irrelevant and the water collected would be safe to use for gardening, washing the car and other type uses around the home.
COLORBOND® and ZINCALUME® are registered trademarks of BlueScope Steel Limited
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