Tag: rainfall

Rainwater Tanks Save The Day

rainwater-tanks-dams
Leslie Dam (reservoir 1,260ha) at 28%. Photo by BW.

Yay – the dams are full, creeks and gullies are running; rainwater tanks are spilling over. Everyone’s happy.

Our three rainwater tanks are full, as you might expect of a region where two water-starved dams reached 100% capacity in just two days.

Not so long ago (2018-2019), things were dire on the Southern Downs, with Warwick’s Leslie Dam at 7.66% (it’s now 28%), and the Granite Belt’s Storm King Dam virtually empty (now 100%).

In January 2020, a national news story told of the local council carting water to Stanthorpe from Connolly Dam in Warwick. The cost, borne by the State Government, was $800,000 a month. Carting ended last week after the March rains brought Storm King Dam back to capacity.

As you might expect, the district deluge was met by the relaxation of severe water restrictions which have been in place now for several years. Southern Downs Council had lifted daily water restrictions from 80 litres to 120 litres in mid-2020. Last week the limit was raised to 200 litres per person per day. There are caveats on this, however, with permanent restrictions applying to the use of hand-held hoses to water gardens or wash cars.

How quickly our mindset changes. We’ve gone from leaving the toilet water to mellow for days and collecting shower water in buckets to using a hose (between 7am-9am and 4pm-7pm) to wash cars. Last time I washed our car I used tank water in buckets.

It’s not so long ago that academics were advocating the use of recycled water to drought-proof houses. Writing at a time when at least seven New South Wales regional towns were in danger of running out of water altogether, Professor Roberta Ryan of the University of Technology Sydney (UTS) wrote that the only real obstacle to using recycled water for a range of purposes was community acceptance.

“Household waste water (which is what goes into the sewerage system from sinks, toilets, washing machines and so on), is a more consistent supply, with 80% or more of household water leaving as waste water.

“Furthermore, waste water goes to treatment plants already, so there is a system of pipes to transport it and places which already treat it, including advanced treatment plants that can treat the water to be clean enough for a range of purposes”.

You might recall that stories like this in 2019 and earlier were met with community opposition. In 2006, Toowoomba, Australia’s biggest inland city, voted against introducing recycled water.

Those advocating re-cycled water (extracted from treated sewage), suggest using it to operate washing machines and toilets in homes and to irrigate parks and sports grounds. Many Councils already use recycled water for those latter purposes.

As the Millenium Drought (1997-2009) worsened, State and local governments started creating rebate schemes to encourage households to buy and install rainwater tanks.

It’s been a hit and miss affair, with rebate schemes ending as quickly as eager queues started forming. Australia’s building code requires tanks to be installed and plumbed in to all new houses, although this differs from State to State. For example Queensland’s local governments can opt-in (or out).

In 2013, the Australian Bureau of Statistics found that 2.3 million households (26%) used a rainwater tank as a source of water, an increase from 1.7 million (19%) in 2007. The ABS said the increase from 2007 to 2013 may be attributed to water restrictions, government rebate schemes, water regulations and water pricing.

South Australia had the highest proportion of households that used water from a rainwater tank (46%), followed by Queensland (34%).

In the absence of an update, extrapolating the annual rate of growth assumes Australia now has close to three million rainwater tanks. This estimate could be rubbery, however. The unknown factor is the numbers of tanks which are self-installed without going through Council.

Although authorities generally do not recommend that households drink harvested rainwater, the supply can be used for a range of purposes, including washing, bathing, laundry and gardening. In some parts of Australia, it may be the main source of household water, while in others, it can supplement existing mains or town water supplies.

Rainwater Harvesting Australia, a committee comprised of irrigation industry leaders, advocates use of rainwater tanks as part of a blueprint for urban water management. A strategy is suggested (for South East Queensland), to consider re-use of storm water to improve the diversity and resilience of water supply. The strategy also recommends rainwater tanks and a basic form of passive irrigation for street trees.

The main criticism of rainwater tanks is that they breed mosquitoes and testing has shown sufficient pathogens in the water to dissuade many Councils from recommending it be used for drinking.

Despite the development of waste water recycling and desalination plants, Australia is still highly dependent upon rainfall as its main source of town water.

A Productivity Commission draft report in 2020 found that direct rainfall (surface or bulk water) or indirect (groundwater) accounted for 89% of all urban water in 2017-2018. The balance was attributed to recycled water (6%) and desalinated sea water (5%).

The report argued for a (national) integrated approach to urban water management, citing seven impediments to such an approach. The key stumbling block is the management of storm water, much of which flows out to sea.

For purposes of this discussion, the report criticises State government policies for mandating recycling or rainwater tank installation without a full cost benefit analysis.

“Many governments, for example, set recycled water targets, mandate the installation of household rainwater tanks or specify that recycled water is to be used in particular applications (such as for flushing toilets).

“These policy decisions are often set without clear and transparent evidence and analysis. They have driven significant investment and have sometimes resulted in higher costs than alternatives and failed to deliver their expected benefits.”

The report cited Marsden Jacob Associates, which found that the costs outweighed the benefits by more than $2000 per tank in most cases. Harvesting rainwater tends to be more costly than supply from centralised supply systems. For example, research in south-east Queensland found that the average cost of tank water was $9.22 per kL, substantially higher than the $4.40 per kL for potable water at the time.

The intangible benefits associated with rainwater tanks include reduced town water and storm water infrastructure costs and environmental benefits (reducing local storm water flows).

They also allow households to have flourishing gardens when water restrictions are in place.

A recent study by the CSIRO (apparently a first), found that 96% of participants identified benefits with their rainwater tanks. The most prominent were: watering during restrictions (88%), reduction in water consumption (82%) and benefit to environment (71%).

Cost-benefit analysis aside, I’d advocate for an integrated approach to installing rainwater tanks in every home and business in Australia. Surely we can solve the apparent downsides (including mosquitoes, water-born disease and contaminants (ash and debris from bushfires).

The key may be for Councils to implement an annual maintenance inspection and issue show-cause notices to those whose systems need work. As the CSIRO study found, only 58% of respondents in an ABS survey claimed to undertake any kind of rainwater tank maintenance. At present, householders have no legal obligation to undertake maintenance other than to minimize public health risks.

The practical advantage of a good rainwater tank system is that it ensures your allotment will dry out quickly once the rain stops.

Meanwhile, we have 9,200 litres of water stored to irrigate gardens through the traditionally dry winter.

It can’t be a bad thing.

FOMM back pages

Moving North Queensland water to Murray-Darling

North-Queensland-Water-Murray-Darling
Barron Falls demonstrates North Queensland water excesses. Photo by Coral Sea Baz

Australia’s mismanagement of water is coming home to roost now, with the highly visible deluge in North Queensland in sharp contrast to the water-starved Murray-Darling Basin.

Far North Queensland residents and emergency workers are still struggling to cope with the worst floods in living memory. Tully, arguably the wettest place in Australia, had 955mm over 27 days since New Year’s Day, about a quarter of its annual rain. Townsville broke all records with 1,200mm falling in just nine days, which accounted for unprecedented flooding and the decision to open the floodgates of Ross River Dam.

Residents of the seaside Townsville suburb of Balgal Beach, seemingly impervious to flooding, found out otherwise.

The Bureau of Meteorology (BoM) recorded North Queensland rainfall totals in January and the first week in February ranging from 1,036mm (Cairns) to 1,325mm (Townsville) The highest weekly total in January was 766mm at Whyanbeel Valley. Crikey, that’s a few millimetres more than the annual rainfall for Australia’s second-largest inland city, Toowoomba.

Last time we were in that fair city (September), the only green grass around was in the city’s three parks, watered by Council to celebrate the Carnival of Flowers. That was the month parts of the Western Downs were added to the 53% of Queensland’s drought-declared local government areas.

Meanwhile in Southern states, BoM made the telling observation that annual rainfall in 2018 was the seventh-lowest on record (since 1900) for the Murray-Darling Basin.  Rainfall was low over the south-eastern quarter of the mainland in 2018, with much of the region experiencing totals in the lowest 10% of records.

This is brought into sharper focus when we are told that parts of Australia’s mainland from around Newcastle in NSW to Euroa in Victoria are now included on the United Nations’ list of the Top Ten Global Water Hotspots (see further reading).

Many readers will be familiar with the crisis facing the Murray-Darling system: blue-green algae, millions of dead fish, the Darling River drying up; water being diverted for irrigation to grow water-intensive crops like cotton and rice. The recently published report by the South Australian Royal Commission found that the 2012 Murray-Darling Basin Plan must be strengthened if there is to be any chance of saving the river system. Professor Jamie Pittock of the Australian National University writes that the Commission found systemic failures of the Basin Plan, adopted in 2012 to address over-allocation of water to irrigated farming. The Commission’s 111 findings and 44 recommendations accuse federal agencies of maladministration and challenge key policies that were pursued in implementing the plan.

Amid revelations of water theft, the awful legacy of dead fish in the oxygen-deprived Darling River and outback towns running out of water, plenty of people are having their say.

This week, South Australian independent Senator Rex Patrick dared to confront the cotton industry, demanding that growers justify the use of water and the right to grow that export crop. (The same could be said of rice, Ed.)

This is a long-running saga. In 2011 an article published by the Permaculture Research Institute explored a report that revealed Australia as the world’s largest net exporter of ‘virtual’ water (exported virtual water is defined as water consumed to create crops, livestock and industrial products for export). The report blamed the agricultural sector for the vast majority of the total volume of water exported from Australia in this way (72,000 gigalitres of virtual water exported overseas every year).

I’m not a scientist, hydrologist or environmental engineer, yet the answer seems desperately obvious. We need to channel and export North Queensland water to the arid south-eastern states and inland Queensland, NSW and South Australia.

One only has to think for five minutes about the Snowy Mountains hydro-electricity/irrigation scheme to see we are more than capable of funding, building and maintaining large and ambitious infrastructure projects.

Sydney food technology engineer Terry Bowring told The Courier-Mail in 2010 about his $9 billion plan to move water from the Burdekin and other north Queensland rivers to arid parts of inland NSW, Victoria and South Australia. Mr Bowring’s plan involved channelling about 4,000 gigalitres of water a year. The water would be transported 1,800kms by canals, with 60% of the water sold to irrigators. The rest would go to cities such as Toowoomba and Brisbane for domestic use.

Mr Bowring told FOMM yesterday the plan was similar to the Bradfield scheme proposed in 1938. Until Mr Bowring’s plan surfaced (he’d been working on it for years), no-one had taken Dr John Bradfield’s scheme forward to include costings.

Mr Bowring said the costings were based on experiences from the US, where he worked for some five years. The system would take six years to build but only four or five years to recover costs.

As with the Bradfield scheme, critics said the Bowring plan was uneconomic and impractical. The telling thing is that it would only take about 13% of the water that flows from the Burdekin to the ocean. Typically, more water flows to sea from the Burdekin than the Murray-Darling Basin and all city dams combined.

Mr Bowring, who is in his 80s, said he has no intention of pursuing the plan, but will make his research available for future use.

The other side of this argument was provided by the (then) Federal Department of Sustainability, Environment, Water, Population and Communities.

The 28-page report generally scotches the idea, which is often raised when there are weather extremes in the north or the south.

“Moving water long distances is costly, energy intensive, and can have significant environmental, social and cultural impacts,” (item 1 under Key Facts).

“Using water that is locally available is generally more cost effective than transporting water long distances. Current studies show that local options, such as water conservation, desalination and recycling, cost around $1–2 per thousand litres; a supply from 1500 kilometres (km) away would cost around $5–6 per thousand litres.”

However the immediate problem is to make the Murray-Darling system a Federal and State priority, no matter the financial or political cost. It is shocking to consider that outback towns like Walgett, Wilcannia and Bourke have either run out of drinking water or are under extreme water stress. These events seem to have flown beneath the media radar that picked up on the early 2018 water crisis in Cape Town (South Africa).

The real danger is the risk to the fragile ecosystem of a river system that spans 77,000 kilometres of rivers over one million square kilometres across four States and the ACT. Environmental challenges include excessive water being diverted for agricultural, the blue-green algae that killed millions of fish, and salinity (in 2016-17, 1.84 million tonnes of salt was flushed out to sea through the Murray mouth).

As the Australian Conservation Foundation summed up, in an advertisement posted on social media:

“The heart-breaking death of these fish is no natural disaster. Powerful corporate interests and their cashed up lobbyists are bleeding our rivers dry. For too long, state and federal governments have let them get away with it.”

Further reading: https://www.fabians.org.au/australia_s_water_crisis (a (long), technical article by Watermark Australia’s Dr Wayne Chamley).

FOMM backpages: