Every person in the world who lives in a house has their own, private, water supply: rainfall on their roof. I can’t explain why people in other countries don’t use rainwater tanks – it’s probably because water from other sources is cheap and plentiful – but in Australia, the world’s driest inhabited continent (Antarctica is the driest), only 7% of capital city households have rainwater tanks and only 13% of all households use them for the main source of drinking water, according to the Australian Bureau of Statistics.

Throughout the 20th century, mains water supply in Australia’s cities and towns had to be installed and paid for, and so it became compulsory for all. Rainwater tanks were prone to backflow into the mains water supply. People who retained them preferred to use this water for free rather than purchase mains water. Although rainwater tanks were never banned, governments made it nigh impossible to install them where mains water was provided. Only in the last several years have some state governments (New South Wales and Victoria) relaxed town planning laws allowing small rainwater tanks to be installed in urban areas without planning approval.

Until 1994, Australia’s plumbing standard did not permit rainwater tanks to be connected to household plumbing used for mains drinking water. However, it was not until 1998 that the Victorian and South Australian governments brought their state regulations into line with the Australian standard. New South Wales applied the Australian plumbing standard to rainwater plumbing only in 2003, and Queensland one year later. Australia’s governments also relied on scare campaigns to warn people off using rainwater. In 2002, the NSW government proposed to require rainwater tanks to be labelled “non-drinking water” until this idea was debunked and scrapped. Even so, the 2006 edition of the NSW standard plumbing and drainage regulation warns “the use of rainwater tanks for drinking purposes is not recommended where a reticulated potable water supply is available”. The Queensland government relied on an anomaly in the 1998 plumbing standard to declare rainwater tanks a high hazard where this is defined as “potential to cause death”. The government’s position changed only when the anomaly was removed in the 2003 edition of the standard. Australia’s governments routinely warn citizens to use rainwater tanks for non-drinking water supply, with the implication being it is dangerous to health.

The nation’s public health authorities recommend that people drink water that is the highest standard available. According to Australia’s enHealth Council “the quality of water from household rainwater tanks is not as consistently high as that provided by well-managed urban water supplies”. However, no Australian health authority declares water collected from roofs for rainwater tanks to be non-drinking water. Human consumption is about 4% of household water use but water must be legally “drinking water” before it can be used in household plumbing used for drinking water. The cost of installing dual plumbing in existing houses, obviously, is prohibitive.

Since 2001, our company has been working to remove these artificial impediments. We also looked for ways to allow rainwater to share plumbing with mains water, and to bring down the cost of tanks. Our rainwater tank connection valve is now patented worldwide and allows supply to switch automatically between tank and mains without backflow and without supply interruption. We have lodged a patent application for injection moulding very low cost rainwater tanks. Low cost rainwater tanks designed for confined urban spaces can be easily provided to all households because tanks can be made at the rate of one tank every 180 seconds.

Consequently, it is now possible to supply every building in Australia with rainwater tanks within five years to provide at least 25% of the nation’s drinking water supply, for about the same cost per kilolitre as mains water, and cheaper than recycled water and desalinated seawater. But do governments genuinely want everyone to use rainwater? We now discover that the impediment is over ownership. Who owns water that falls on a person’s roof in Australia?

In Victoria, water that falls on a person’s roof is the property of that person: no rights to this water vest in the state. The Victorian government is to be commended for making its position transparent. In contrast, the National Water Commission says all water in Australia vests in governments – including water that falls on a person’s roof. It proposes an “entitlement regime” should rainwater tanks be adopted on a large scale “such that their existence impacts significantly on the integrated water cycle”. Rainwater, obviously, would become less competitive. Is this the intention?

New South Wales and Queensland state governments (including oppositions) refuse to say whether or not water that falls on a person’s roof is the property of that person. However, water Acts in Queensland (section 19) and NSW (section 392) do not vest rights to water that falls on a person’s roof in the state. This is why these governments (and oppositions) will not comment. South Australian, Western Australian and Tasmanian governments all consider a person’s roof and the surface of the ground to be the same thing, because rights to surface water vest in the state. These claims are untested. The reason that governments (with the exception of Victoria) resist private ownership of the right to use water that falls on a person’s roof is so that they may regulate, control and ultimately, tax, its use.

When water that falls on a person’s roof is the property of that person, they combine rainwater with mains water in their household plumbing system by choice, and on their own legal responsibility. Federal and state governments, and their oppositions, bribe householders with ever increasing subsidies for high cost rainwater tanks.

Governments and oppositions choose to ignore the clear and immediate opportunity to make rainwater the nation’s lowest cost source of additional water supply.

Ken Matthews, Chair, National Water Commission writes: Greg Cameron’s piece on regulating the rain is knowingly and mischievously wrong. Mr Cameron knows the National Water Commission has not proposed, and is not proposing, an entitlement regime for rain water. He knows the Commission has never mentioned, let alone proposed a tax on tank water. He knows also that the Commission wants to foster all “new” sources of water such as rainwater through a positive and stable regulatory environment. He knows all that because last time he got a newspaper to run his story I put out a public statement making all those points clearly for his benefit.

Greg Cameron, Urban Rainwater Systems Pty Ltd, writes: The National Water Commissioner, Mr Ken Matthews, was my source for claiming that the federal government proposes an “entitlement regime” for rainwater tanks. He wrote on 25 August 2006, “As we understand it, governments have not yet considered the capture of water from roof [sic] in rainwater tanks to be of sufficient magnitude to warrant the issuing of specific entitlements to use this class of water. However, if rainwater tanks were to be adopted on a large scale such that their existence impacts significantly on the integrated water cycle, consideration could be given to setting an entitlement regime for this class of water.” The Commissioner alleges my reporting of his statement was knowingly and mischievously wrong. In relation to a tax on rainwater, my view is that “entitlement regime” means licence, and licence means tax. The Commissioner also says water that falls on a person’s roof in Australia is not owned by that person. This statement is not supported by the Victorian government for Victoria and, as of 20 March 2007, is not supported by the NSW Labor Party for NSW. In my view, it is also not true for Queensland and the Premier, Mr Beattie, was asked yesterday to clarify the matter. (The governments of South Australia, Western Australia and Tasmania all claim that a person’s roof is the surface of the ground for water collection purposes. In all states, rights to surface water vest in the state.)