Rembrandt makes a good point about most water use being in agriculture, meaning that the absolute gain from reduced urban household use would be relatively small. If we’re to allow water to be used in ways most valuable to the community, a sensible pricing policy must be combined with opportunities to trade water between sectors. While Goeff is right that not all water used in agriculture could feasibly be diverted to urban supply (nor would this be necessary or even desirable), there are enough opportunities for trading to alleviate some urban water pressures and to encourage more efficient use by all sectors – households, industry and agriculture.

Rhian,
I argee with your sensible reply.

Perhaps Rembrandt hails from Melbourne where agriculture and city do not have the Great Divide as Sydney has, making it more feasible to interchange water use.

Wow!

Another article on how outrageous it is that we consumers are paying so little for our water. It makes me feel ashamed of my profligate past when water was unmetered, Swirlons, garden sprinklers and backyard waterslides were forever on the telly, and more than once I left the hose on overnight and woke up to a deluged yard. And I cannot remember ever wondering whether flushing the dunny was worth it.

The reality is that there is only so much cheap water available, and when you keep packing people in, as governments of all tiers and persuasions in this country seem obsessed with, the cheap water runs out. Water is a commodity, and its price is determined by supply and demand. The idea of water having intrinsic value is idiotic. Why be so coy? Why not acknowledge that the water crisis and the prospect of a fourfold increase in the price of water is just another disastrous consequence of a population growth policy which a majority of Australians have long opposed?

Ah, the dear old government again. They have not wanted to set the price of water at a realistic figure in the past because they believed that the voters would rebel. Now there is a great rush to spend more of our money on alternative supplies. Maybe one day they will wake up and let the market do the job properly .......... Nah!.

There are some strange costings above. One millimetre of rain
produces one litre of water from one square metre of roof. So the numbers for Sydney with 960mm/yr are 0.96 kilolitres for each square metre of roof. So the entire requirement for 225Kl per household can be met by the now median roof area of 250m2.

Smaller houses generally have smaller gardens and therefore have smaller water requirements. But if we assume that Sydney will remain at 80% of mean annual RF and it is evenly spread over the year then clearly, each square metre of roof will deliver 80 litres of water each month. So the median roof size of 250m2 will deliver 10,000 litres each month.

So tell us all, Greg Cameron, why would anyone who is properly informed on this issue bother pussy footing around with four dinky little 640 litre water tanks? Even if they were all bone dry it would only take 20mm of rain for them to overflow.

And all the talk about charging more for water is bunk because the market is defined by alternative supplies. Those alternative supplies will come from water tanks (decent sized ones) and operate as a price reality check.

A 9,000 litre tank still costs only $1600 and even after adding extra for plumbing and pressure pumps etc, a total cost of $2500 is still only $200 a year at 8% interest which will deliver 225Kl at 89 cents/Kl.

The people talking up $4/Kl water prices will only succeed in chasing so many customers away from some very expensive public water infrastructure that they will become uncompetitive due to insufficient turnover.

Four dinky little 670 litre rainwater tanks collecting all of the water discharged from a house in Sydney with 175 square metre roof area will yield 75KL each year for 30 years at a cost of $1.25/KL. The collection efficiency is 45% - more than half of the water that falls on the roof overflows from the tanks into the stormwater system. (Rainwater tank yield is a function of the rate at which water is removed and not the rate at which it enters: a full 9000 litre rainwater tank overflows at the same rate as four full 670 litre rainwater tanks.)

The larger the tank, obviously, the more rainwater that is collected. Larger tanks cost more, are more expensive to install and frequently are impractical in confined urban spaces. Perseus is to be commended for wanting to convert his backyard into a rainwater tank storage area to enable him to obtain more water at a cost of 89c/KL. Large storage capacity is feasible for new homes where it can be included as a design feature, but for the 97% of existing homes that do not collect and use rainwater the option of installing four 670 litre tanks that occupy minimal space is now available.

An average household uses 150KL of drinking water indoors each year and thus rainwater can provide at least one-half of indoor water requirements. A million Sydney households will provide at least 75GL of water each year.

The cost per KL of desalinating seawater is $1.73 - $1.98; and indirect potable re-use (sewage recycling) is $2.23 - $2.61.
Source: Marsden Jacob http://www.marsdenjacob.com.au/Documents/MJA_2006_ResearchNotesSecuringAustraliasUrbanWaterSupplies.pdf table 2.

Rainwater is dismissed as an option by the NSW government as being too expensive – it estimates $4/KL.

Are rainwater tanks a cost of water or housing?

They are a cost of water when rights to the water are vested in the government.

They are a cost of housing when a person owns the water that falls on their roof.

Whose property is it?

Greg Cameron