Sunday, October 30, 2005
Riding out the storm
Brisbane and South East Queensland appear to have ridden out the latest water crisis. A dry summer in 2004-05 and little substantive rain throughout the winter, coupled with Brisbane residents’ traditional profligate use of water, had seen dam levels plummet.

Level 3 restrictions were just a week away from imposition, before some early summer rain in the last two weeks rescued us from the 30% dam capacity trigger point.

Significantly, much of this rain has fallen from fleeting storm cells, rather than bands of showers. As a result, rainfall is short and sharp and also very localised. One suburb or one catchment could cop a bucket load; a neighbouring area could be passed by. So the age-old whinge from water engineers “its not all falling in the catchments” remains half-true.

Brisbane secures its water from one huge dam and two other smaller dams out to the west – Wivenhoe, Somerset and North Pine. Wivenhoe and Somerset lie in the same catchment area. As a proportion of the region, this catchment represents only a small proportion. Surely, the answer lies in decentralising water harvesting, so that each house, neighbourhood and suburb captures its own supply.

Wivenhoe et al, in the short to medium term, would no doubt continue to provide the bulk of the supply, but as localised catchment penetrates further, these giant storage dams would become merely suppliers of last resort.

The introduction of level 2 water restrictions (when the dams hit 35%) brought on a huge community response. Theoretically, even with level 2 restrictions, a resident could still throw as much water on their garden as they could possible ever want to pay for, provided they do it on alternate days and between 7pm and 7am. But the recent introduction of tightening restrictions has been accompanied by a massive publicity campaign to ‘watch every drop’.

Residents are now using water more smartly and using less of it. Ironically, the community has been so successful in reducing their consumption that the Lord Mayor of Brisbane has flagged there are budgetary implications for BCC – residents are not using enough! Consumption is at 75% of the target usage.

For most reasonable people, many of the initiatives and tips being dished out by the water authorities must seem ludicrously obvious. I find it astonishing that residents must be told to turn the tap off when brushing teeth, not to use water to blow the leaves off their concrete driveways or not to water their lawn in the middle of the day. But Brisbane residents are at last receiving a crash-course in sensibility. People living on the driest continent on the planet cannot continue to be the highest per capita users of water.

The highly localised and variable nature of the rainfall and the success of the level 2 restrictions both suggest that the current water supply paradigm is ludicrously outdated and wholly unsustainable.

Why take the chance that water will fall in one (albeit large-ish) catchment, 60 kilometres from where people need it? Why not hedge your bets and instead rely on localised storm water harvesting, implementing a redundancy system?

First, capture water at domestic level, then at a community level and then only finally rely on regional, inefficient system as a last resort. Payment for water would be subsequently graded – that which you capture would be free, that captured locally, paid locally and the supplier of last resort, paid to centralised water distributors.

Secondly, if and when dam levels ever recover, why lift the water restrictions at all? The recent publicity drive has forced people to reconcile themselves with smarter use of water; no one has suffered; apart from a few extra mozzie bites.

The benefits are obvious:

Security of water supply would be improved, when the harvesting of storm water is decentralised to all parts of the region, rather than rely on rainfall in just one catchment.
Water quality in the creek systems would be improved, if run-off into the creeks is regulated by localised storm water catchments. Instead of experiencing an empty-full-empty cycle, wreaking havoc on creek ecosystems, they would experience longer periods of median flow.

Economies would be achieved through delaying (and probably even offsetting) implementation of additional major infrastructure to meet a rising demand on the reticulated system. Additionally, wiser use in the home reduces the rates of grey and black water flowing into sewerage systems, thus delaying implementation of additional water treatment infrastructure.

System efficiencies would be achieved through a shorter reticulated system. Currently 30% of water taken from the dams for delivery to homes is lost to seepage, over its 60km journey to your tap.

Responsive water systems would make settlements more ‘population proof’. If SEQ is to accept another million people over the next 20 years it makes sense to link the level of water harvesting to the number of people reliant on the supply. Where water is captured in the community – or even within the curtilage – this link is retained.

It sometimes takes a (near-) crisis to get people thinking about the limitations of current models of delivery, surely now is the time for imaginative thinking on this issue. For too long, just building ‘more big infrastructure’ has dominated public policy.

See also:

• The dry continent gets thirsty
• Reclaiming the streets

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