Most years approximately 250 tonnes of water fall on the average house roof.
Cool Kiwi have developed a collection system that can optimise the use of this "liquid gold".
I have long held an interest in self-sufficiency and sustainable resource use. With the introduction of "user pays" charges for water and wastewater I have developed my interest further. It has been my view that 95% of water storage is for 5% of the time. With the consistent frequency of rain in Auckland I considered quite small storage on site could supply most of our needs, but the amount of storage for the extremes is unattainable. About two years ago I devised a computer simulation that confirmed my expectations.
The trick was to be able to use site-collected water whenever it was available but to switch to town supply at other times automatically. 18 Months ago I designed and installed such a system. This has been very successful and we now supply over 65% of our water from our 160 square metre roof. Due to limited space we only have a 4000 liter (900 gallon) tank which is 1.8m high and 1.8m diameter.
WHAT I DID
The system I have installed includes ultra violet light disinfection and micro filtration that provide protection from bacteria and Giardia. The quality of water from this treatment usually exceeds city water and has the advantage of not containing chlorine or fluoride additives when collected from the roof. It also has the added quality of being very soft. I have information available confirming the quality of home treated water from this equipment.
In normal operating mode the system is completely automatic, apart from filter changes and the like. For unforeseen emergencies, replacing a short length of pipe will revert the system to town mains. In many cases it is quite simple to retrofit this system to existing houses.
HOW TO JOIN IN
Just send me the size of your roof and an idea of your winter and summer water use (this is on your water bill) and I will run the data through my computer and give you the likely savings you can achieve with various tank sizes.