5 million litres per day? This equals 1.8 billion litres per year. Which equals 1.8 million cubic metres per year
According to
this page, total consumptive water use in Australia in 2004/04 was 18.8 Billion cubic metres. This equates to 18,800 million cubic metres per year.
So the difference this idea would make is 1.8/18,800 = 0.01%
Every little bit helps of course but we might need to do something more than this!
BTW the same page says the average cost of water and sewage per household is $60 per month, with an average use of 280 litres per day per person.
Of course for industrial and agricultural users the cost is much, much less...
So, with residential use accounting for only 11% of total water consumption in Australia, it might not be the place to look if we really want to save water.
But don't tell anyone - ask anyone on the street and they will all tell you that taking shorter showers and using waterless urinals will save us!
A classic case of the very successful use of spin by politicians to try to convince us that they are "doing something" about our "water shortages" by telling you what days you can water your lawn...
If only we were smarter than that.