Ludwig, my reference to you not having heard of rainwater tanks was in relation to the fact that you have been told on numerous times that population growth is not a threat to water stocks or existing supply if every new house is required to install a decent tank. Yet, you continue to flog population growth as a threat to everyone else's water security when you know it is not. All you do is distract people from more important aspects of the water issue. Growth does not automatically equal increased demand for mains water.

On the issue of tank water costing, the key to keeping tank water costs low is how much volume is captured and used each year. The more times it fills up and empties the cheaper each tank full becomes. And this must be balanced against economies of size. A 5kl tank costs $1000 or $200/Kl to buy while a 22kl tank costs $2700 or only $123/Kl of storage capacity. But these savings are lost if the big tank has insufficient roof area to keep it reasonably full.

And this is why I keep repeating that 13.5kl of tank capacity is the optimum size for the average house.

Those concerned about bird droppings on the roof ending up in the tank ignore the reality on a normal Australian roof. They are damned hot places. If you deposit a naked 90kg human without water on a Brisbane tin roof he will be dead by the end of a normal day. In a week he will be completely dehydrated with minimal biotic action remaining. A flying fox turd is turned to hard baked enamel in a day and is converted to inert carbon dust in a few days by the same radiation used in the water purification plants. But the amount of UV exposure on a roof top is astronomically greater than what is applied in the treatment plant.

You already have a low cost, fully functioning, solar powered, UV treatment plant on top of your house. And it works very well indeed.

"You have been told numerous times that population growth is not a threat to water stocks if every new house has a decent tank."

That is arrant nonsense.

Increasing population in Australia is only significantly affecting Sydney and thus NSW, according to the SHA maps I have presented. The greater Sydney's population grows, the greater will be the wastewater induced micro climate zones I have described off the East coast of NSW. Tanks will only increase immigration for profit, water overuse, and thus oceanic wastewaters. The cost to fix the wastewater problem will grow exponentially with increasing population and will be unaffordable. ITM NSW will experience permanent drought. It won't Global Warming!

This article http://www.smh.com.au/news/national/theyre-turning-wine-into-water-in-griffith/2006/08/14/1155407741502.html
correctly implicates evaporation from NSW waterways as a major problem in NSW drought. But that evaporation is only a problem while coastal ocean micro climates attract it out to sea. Further, the damming of and cultivation of the Griffith wetland is a good move. But this won't solve the drought problem while coastal populations and their wastewater rivers to sea increase and steal all the evaporation from the NSW heartland.

The solution:

* Stop land releases in Sydney and coastal areas. Divert immigration to SEQ. Let Beatty have the headaches. Tell Costello to butt out.

* Continue developing wetlands like at Griffith. Thousands will be needed.

* Gradually form RESPONSIBLE PPPs for sewage diversion to wetlands around Sydney. Shut down deep ocean outfalls where fiscally possible. Make these PPPs fully accountable up front to the public with plebiscites.

* The damming of these wetlands(described), causes minerals to be locked in the bottom of the dam. This, water overuse and accelerated ocean dumping are why dams have failed all over the world. To stop this all tributaries entering wetland dams in NSW must be protected by smaller wetlands whose siltation and vegetation can be periodically harvested and spread over farms.

All these measures are essential to stopping our drought and ALL of NSW, city and country, have roles to play.

NSW, together we can do it !

Sylvia--

One million Sydney houses using rainwater tanks will yield 75GL/Y @ 75KL/house. Installing 1M rainwater systems costs $3B ($3,000/house) and yields 2,250GL over 30 years costing $1.33/KL. Operating cost per house is $900 over 30 years or $0.40/KL. Combined capital and operating cost therefore is $1.73/KL. Sydney mains water costs $1.23/KL - rainwater costs $37.50 per year more than mains water.

The Sydney Metropolitan Water Plan Progress Report noted the opinion of some experts that ‘water has historically been undervalued’ in Sydney. It also noted that construction and operation costs of a 125 ML/day scaleable desalination plant would raise Sydney Water customer bills by about $60/Y. (Sydney’s Water Supply, Metropolitan WaterPlan, 8 February 2006, p8.)

The NSW Auditor-General reported in 2005:

“... We have reported over the last three years our concern about Sydney Water’s ability to fund the replacement of its system assets given the age and condition of the system and relevant pricing structures. The estimated cost of replacing Sydney Water’s assets at 30 June 2005 was $20.0 billion ($18.2 billion at 30 June 2004). However, based on Sydney Water’s estimate of the assets’ ability to generate cash inflows, their value was reduced to $11.2 billion ($10.8 billion).

“... We believe that the gap between Sydney Water’s ‘replacement’ asset values and their cash generating capability is significant and may need further analysis by key stakeholders. IPART has recently granted real price increases to Sydney Water in its 2005-2009 determination. This will help to alleviate some of our concerns.”

“... A desalination plant represents a viable method of supplementing supplies of drinking water for Sydney. Sydney Water estimates that it would cost $2.0 billion to construct a 500 megalitre/day desalination plant and approximately $100 million per year to run it. On a purely financial basis, this compares favourably against recycling water into the drinking water supply in established areas, where Sydney Water estimates that it would cost $2.8 billion to build the facilities to recycle wastewater, and a further $140 million a year to run the facilities.
Source: http://www.audit.nsw.gov.au/publications/reports/financial/2005/vol4/73-0955_SydneyWaterCorp.pdf

Rainwater tanks are competitive.

Greg Cameron

A desalination plant represents a viable method of supplementing supplies of drinking water for profiteers riding the back of an usustainable and unwise 100,000 people and 50,000+ car immigration loading every year on Sydney. And NSW you will pay not only for their water but all the other costly infrastructure that is needed to support this invasion of your state.

This strategy is in the interests of Ghibelline state government officials in line for post ministerial favours and jobs. It is in the interest of Costello and Howard who are shepherding Melbourne at the expense of Sydney in order to maintain Federal power. It is NOT in the interests of the general NSW public.

NSW you can beat this! STOP immigration into Sydney NOW and build a NSW future on QUALITY and not untrue, untried and untested NUMBERS of neo-electors. Qld will gladly take up all the excess immigrants and we can pick and choose the best skills after Qld has melted down in a debased, overcrowded mire of humanity. These skilled people will be only too glad to shift to a state run on QUALITY ideals.

And Sydney's water problem is not the issue for NSW. The issue is the perpetual drought caused by ever increasing rivers of muck pumped out to sea off the NSW coast and through Deep Ocean Outfalls off Sydney where unsustainable numbers of people are settling.

I have listed the ways this can be reversed and the NSW drought can be broken.

NSW ... take control of your state!

Your only enemies are a small minority of bigmouths with lots of YOUR money, deep pockets and NO respect for your future.
I think we all know who they are.

“But let us leave the history and the blame game of over allocation to history.”

One would imagine, incorrectly it would seem, that Mr Turnbull would be aware of that wise adage "Those who fail to learn from history are doomed to repeat it"

We are entitled to better than this self serving rhetoric from our national leaders. He could afford to heed Ludwig's postings on this thread for some simple root-cause analysis and problem solving.

Greg,

You cannot add together amounts of money that relate to expenditure at different times. Or at least, if you do, you don't get meaningful answers.

Consider this. Suppose that a kilolitre of water today costs $1. What is the cost to me, today, of a kilolitre of water to be delivered in fifteen years? First we have to work out how much a kilolitre of water would cost in fifteen years. Suppose inflation's running at 3%, and the price rises in line with inflation. Then in 15 years, the price will be $1.56. Now suppose that the interest rate is 7%. I don't have to put aside $1.56 today, because in the intervening 15 years, the money will earn interest. In fact, $1 today will be grow to be $2.78 in fifteen years. So to have $1.56 in fifteen years, I only need to put aside 56 cents today.

When you buy a water tank, you are effectively putting aside money today to buy water in the future. To compare that cost with the cost of buying that water from the mains, you have to compare it with the amount you'd have to put aside *today* to buy that future water, and that's a lot less that the simple sum of the amounts paid in the future.

This is discounted cash flow. See http://en.wikipedia.org/wiki/Discounted_cash_flow

Sadly, this is little understood by the public at large, which means that people generally do not understand the investment decision made by governments.

Sylvia.