Our rainwater tank ran dry this week! We had already switched the house back to mains water at the beginning of October, in the middle of spring, but now in late December there is no more water for the vegetable garden. This is the first time since 2009 (in the last summer of the 10 year Millenium drought, when we doubled our storage capacity) that we have run out of rain water.
We installed a 10,000 L tank in September 2003, and a further two 5,000 L tanks in December 2009. On a suburban block with two adults and an extended vegetable garden we have been almost self-sufficient in water. We had 12 quarters since 2009 when our water use was 0 L, including 21 months through the wetter period of 2010-2012.
However, this year our mains water use will spike again in summer. For the third year in a row in Adelaide, there has been too little rain in the spring months to top up our storage tanks. We have had to return to mains water for household use in the summer each year since December 2012, while still using rain water on the vegetable garden. Rainfall has been seriously below average in August, September and October. A downpour in late November brought only 7 mm, not enough to re-fill the tanks.
This year there were unseasonal rainfall peaks in February and April, and above average rain in June, but then the rain stopped suddenly in the middle of winter, with almost no rain from the end of July. Adelaide is well-placed for using rainwater tanks, with historic weather patterns conducive to providing regular top-ups of storage. Disturbingly, these rainfall patterns failed in 2012, 2013 and again this year.