Jane Powerson collecting rainwater
Rainwater: it's completely free, but it's a precious thing, being naturally soft and without lime. In the days before hair conditioner it was used by women for washing their hair, to impart silkiness. Shampoo or soap makes lather more readily in rainwater, so less is required - and less goes down the drain, which means there's less pressure on sewerage and septic systems. It is the best thing for watering acid-loving plants if you live in a hard-water area, and for topping up a garden pond or aquarium.
Yet, in Dublin, a modest house (with a footprint of 50 sq m) lets 22,000 litres of the stuff flow away every year. That's how much rain falls annually on the roof and down the drainpipes. And in Dublin especially - with our high population and a large number of commercial growers in the north of the county - our water system is under particular stress.
The easiest way to collect rainwater is to attach a water butt to your downpipe with a diverter - and use it for watering the garden.
You can make your own from an old oak barrel, a plastic drum, or even a recycled oil barrel. Be sure that you fit a lid to avoid accidents, and to prevent insect larvae from setting up home in the water. Install a tap, and build a secure plinth to raise the container above ground level, so there's room for a watering can underneath.
If you've no handyman genes in your make-up, then a less painful solution, in the form of a plastic water butt (with a capacity of 100 to 350 litres), can be found in DIY stores or in green-minded outlets such as Ecoshop in Glen of the Downs (01-2872914; www.ecoshop.ie). Residents in the Fingal County Council area are lucky, as the local authority has several hundred water butts for sale at a subsidised price of €40.
Made in Ireland from recycled plastic, and complete with a stand, child-safe lid and rain diverter kit, they are available from the Balleally, Balbriggan and Estuary recycling centres, and at the council offices in Blanchardstown (01-906210).
For those who are building a new house, refurbishing an old one, or who don't mind digging up their property in the cause of sustainability, an underwater storage tank (holding anything from a thousand to several thousand litres of rainwater) will collect rain from the roof.
Filtered rainwater can be used in the garden, and for clothes washing, house cleaning and flushing toilets - which together account for more than 50 per cent of our water usage. If you harvest rainwater, you do the planet a double favour: you're not using potable water (which carries the payload of processing and chemicals and labour), and you're decreasing the amount of rain run-off that ends up in waste water treatment plants.