Recycled water - Purple pipe part of the green solution ...

Excerpt from the Australian:

Purple pipe part of the green solution

8 November 2008

Purple pipes are being seen on construction sites all around Australia, but the reasons are not aesthetic.

The pipes, on new housing developments sprouting on the edges of major cities and towns, are meant to provide a distinctive system for the delivery of recycled, treated water. The purple pipes supply water for purposes such as laundry washing, toilet flushing and irrigation, while water for kitchens, showers and bathrooms is carried in white or blue pipes.

"The idea of colour-coded pipes is to reduce the chances of accidental cross-connection," says Professor Jurg Keller, director of the Advanced Water Management Centre at the University of Queensland. "It works fairly well, but you can never assume perfection, and of course there is always the possibility that treated recycled water might be accidentally ingested.

"So the level of treatment of the water going through the purple pipes has to be quite high -- and it is. Any pathogens are eliminated by the processing, although there might be some low-level chemicals present. But it is safe enough to drink. It is classified as Class A+, which is very high by world standards."

The impact of purple pipes on overall water supplies can be very significant. For example, the master plan for the new Pimpana Coomera housing development on the Gold Coast projects a reduction of up to 84 per cent of water from reservoirs due to the use of recycled and captured water. The treatment plant for the development will initially produce nine million litres of recycled water a day, and the long-term plan indicates production of 60 million litres by 2056.

The use of purple pipes is governed by the standard AS/NZS4130, which sets out how the pipes are to be used, connected and certified. The Plumbing Code of Australia has incorporated changes to the manner in which plumbing regulation is managed to take account of the new system, and several plumbing supply companies have developed specialist connections, outlets, and fittings.

"The purple pipe system has been accepted pretty quickly by the housing industry, and in some new housing developments it is even being used as a selling point," says Keller. "Some water authorities are offering discounts for the use of recycled water, so there can be cost benefits to the user as well as the environmental benefits to the community.

"Australia is considered to be a world leader in the quality control of recycled water, but the big problem is the installation cost. A dual reticulation system really only makes economic sense to install when a new suburb is being built from the ground up, and where the density of housing is fairly high. Where the number of houses is small, especially if they are spread out, the economics don't really work, especially when you factor in the energy costs of treating and pumping the water. Retro-fitting existing houses is very unlikely to be economic in the foreseeable future."

A feasible alternative in the use of recycled water, Keller believes, is the addition of recycled water to water supply reservoirs. This is being implemented in Brisbane, with validation testing of the water quality from the recycling plants currently under way. The first release, into Wivenhoe Dam, is likely to take place in early 2009. The recycled water to be added to the reservoir will be treated to a higher level than that used in purple pipes.

This method of supplementing fresh water supplies is already used in water-short places around the world, including Singapore, California, and several European countries.

Keller accepts that some people in Australia have a deep-seated concern about the addition of recycled water, regardless of the level of treatment, to fresh water supplies.

"I see it as a matter of perception more than a matter of scientific fact, but everyone is entitled to their views," he says. "Opposition will probably diminish over time, as the use of treated water becomes commonplace without incident. And those who are currently opposed to supplementing fresh water supplies with highly treated recycled water should consider how water gets into the reservoirs in the first place. Much of it arrives from streams and rivers that pick up dirt and debris on the way to the reservoir. It might be natural, but that does not necessarily mean it is perfectly clean.

"And rivers themselves have been used as sources of freshwater for a long time, even though they might have had wastewater put into them, either naturally or artificially, at a point upstream."

While valuable, Keller does not believe the purple pipe scheme should be made mandatory, even for new housing developments.

"In Australia, we have generally been quite wasteful with our drinking water, but the recent water shortages have really demonstrated that we can be much more efficient with our water use," he notes.

"In my view, a better alternative than making laws about the use of purple pipes would be to require efficiency measures and to encourage that a certain proportion of the water used in a home comes from sources other than freshwater reservoirs. That might mean from rainwater tanks, or from groundwater, or from purple pipes. We have already seen some water authorities around the country moving in this direction, and it has been quite successful.

"This is, in general, the way that water supply is going: towards a mix of quality levels, related to specific purposes, with freshwater allocated mainly to drinking and personal uses. Public awareness of water shortages is high enough to support a move away from the traditional single-source approach. One way or another, recycled water is here to stay."

See - Purple pipe part of the green solution.

So Dr Keller is another QWC aligned person relying on the 'poo in the dam' argument to justify potable reuse.

Singapore is only 1% - amazing how they never specify that. And they wonder why people don't trust them.

Also funny how purple pipe recycled water is a workable solution for new subdivisions and industrial applications in other parts of Australia but not South East Queensland.

Pouring recycled water into dams for human consumption is the quick and dirty solution to water source issues ...