Hoaxed: The Australian Conservation Foundation cons the media on rainwater tanks

If you turned on the radio or opened a newspaper last Monday you would have been forgiven for thinking that a group of economists had stumbled upon a solution to Australia’s urban water crisis.

A massed rollout of suburban rainwater tanks – at the rate five per cent of households each year - would apparently be cost competitive with dams and desalination plants as a means of securing access to water.

The claims were made by the Australian Conservation Foundation, which with two other environment groups had commissioned an examination of tanks by Marsden Jacob Associates, Australia’s leading consultants on the economics of water.

Not only would a tank in nearly every house be cost competitive, it would also store water more efficiently than dams, “creating a virtual dam from the rooftops across our suburbs”.

The ABC loved the story.

On Radio National breakfast in the morning, on the TV news at night, and on our own 666 ABC Canberra in the mid-morning the Conservation Foundation spruiked the benefits of suburb to suburb rainwater tanks and lent heavily on the reputation of Marsden Jacob to give the idea weight.

The ACF’s Kate Noble told Canberra’s ABC: “What we are suggesting in our report that we commissioned by Marsden Jacob, very respected economic consultants, is that we have a targeted tank program to roll them out broad scale.”

Asked whether there were real economics behind the idea she replied.... “This is exactly why we have done this report and why it has been put out by Marsden Jacob because they are respected economists. They do the research for the National Water Commission.”

In research for the National Water Commission Marsden Jacob have twice found that rainwater tanks are a very uneconomic means of obtaining urban water, and absolutely useless for finding water during in a crisis.

Perhaps unbeknownst to the ABC and some of the newspaper journalists who wrote up the ACF press release, Marsden Jacob also said it in their 30-page report to the ACF.

Table 2 early in the report makes clear that in all but exceptional circumstances suburban rainwater tanks obtain water at a greater cost per kilolitre than dams, desalination and recycling. They can even be more expensive than the cost of pumping water long distances, which reaches $9 a kilolitre. By contrast reusing storm water and buying rural water costs less than $2 per kilolitre.

The ACF told interviewers that if governments put rainwater tanks in 5 per cent of households each year Sydney could delay the need for a desalination plant for a decade.

Marsden Jacob had told it that could only happen if 70 to 78 per cent of properties got rainwater tanks. Many of those tanks would catch water at a very high cost per kilolitre.

The ACF late last week defended its treatment of the report. Its urban water campaigner Kate Noble said that in publicising these sorts of report groups such as the ACF “always emphasise some parts and not others”. She said the ACF had been trying to get rainwater tanks onto the agenda and was not responsible for the actions of the media.

Marsden Jacob’s principal John Marsden said last night that he was disappointed with the “enthusiastic” treatment of his report by the ACF. He said he had gone out of his way not to publicly criticise the ACF and that it remained an organisation for which he had great respect.