Swimming pools + water shortages

I've recently moved to Adelaide, and love it. The only thing I don't understand is this: South Australia is supposedly Australia's driest state and yet it seems almost every second person has a swimming pool.

What's the problem with that, you may ask? Well, if SA is supposedly such a dry place, why are billions of litres of fresh drinking water wasted in filling up peoples' swimming pools? We have restrictions on watering the garden, for goodness' sake, but millions of litres either evaporate every day, or simply run down the drain - unbelievable!

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