Rain

I’m sitting here in my study at 0714hrs and enjoying the sound of the rain which has become familiar over the past week. My rainwater tanks are now full and I’m wondering — as I often do when it rains like this — whether I should have shelled out for another proper 4000 litre polyethylene or colorbond thing when extending the original installation instead of improvising with 2 IBCs and a 800 litre bladder. It was a lot cheaper, of course, but I’ve sacrificed substantial capacity.

It’s too late to do anything until the IBCs or bladder fail, as they will eventually. The IBCs are not UV stable and the bladder is easily damaged, but they should last at least another three years.

The rain situation has been a bit of a concern because even in Sydney we haven’t had much since at least last December. There have been very few tank-filling rain events in the last six months–

No. I’ve just checked my spreadsheet. There have been no overflow events since last October. Before this week, the main tank’s highest volume was about 3750 litres (out of a maximum 4000), and that was in February. It had fallen to less than 500 litres by early May, and I’d started to use the bladder for watering the garden. The two IBC’s remained full throughout this period.

The main tank was installed in January 2007. In March 2009, system capacity was extended by 3000 litres. As of today, 91799 litres of rainwater have been drawn from the tanks. Because of this week’s rain, there are 7000 litres to use before I’m forced to revert to the reticulated supply.

The tank system is connected to a toilet, the washing machine and two garden taps.

According to Weatherzone the current Sydney rainfall stats for May are:

Wettest this month: 47.8mm, on the 19th
Total this month: 105.4mm, over 11 day(s)
Long-term average: 120.7mm, over 11.8 day(s)
Wettest on record: 585.0mm, in 1919
Driest on record: 3.0mm, in 2008

I’ll update at the end of the month.

Meanwhile, we’re expecting more rain for the next week or so.

Update (final figures for May):

Wettest this month: 47.8mm, on the 19th
Total this month: 168.4mm, over 17 day(s)
Long-term average: 120.7mm, over 11.8 day(s)
Wettest on record: 585.0mm, in 1919
Driest on record: 3.0mm, in 2008

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