Louisa Pearson: “Yes, the rain keeps the landscape green, but it also makes our hair frizzy”

H OW much water does the average pint of beer contain? Note: this is a trick question. The answer is 170 litres. I realise that at first glance this is akin to trying to convince you that the earth is flat, but I’m talking about ‘embedded water’, so I’m sure you’ll agree that it is possible for the beer to contain both one pint and 170 litres of liquid at the same time. It’s like the beer exists in parallel universes. Phew, not even the end of the first paragraph and it all sounds a bit sci-fi. More about embedded water later.

World Water Week (www.worldwaterweek.org) kicks off today, an annual shindig where people with an interest in the planet’s water resources get together in Stockholm to debate the big issues of the day. But when you live in Scotland, it can be hard to feel really thankful for water. That downpour hammering down from the sky throughout August ruins our plans for barbecues, picnics and the like. Yes, it keeps the landscape green, but it also makes our hair frizzy. So when environmentalists lecture us about always switching off the tap while brushing our teeth we think, fine, we’ll do it, but we’re not really buying the argument for why we should – other than because we feel bad about severe water shortages in far-flung parts of the world.

The website for Waterwise (www.waterwise.org.uk) has some good tips for saving water: I intend to follow the suggestion of using leftover water from my night-time glass by the bed to irrigate my houseplants, which are always grateful for any liquid that comes their way. It also suggests a cistern water-displacement device in the loo and installing a butt in the garden, while reminding us that if everyone in the UK who usually leaves the tap running when brushing their teeth turned it off instead, we would save 446 million litres of water (enough to supply 2.9 million people for a day). This is all good advice but in the rainy north it doesn’t feel like a pressing issue. This is where embedded water comes in.

It may be a step removed from pouring a glass to drink or flushing the toilet, but embedded water is the water used to produce all the food and non-food products we consume every day. In the case of the beer, that’s everything from the water used to grow the grain to that used to wash the delivery lorry. About 70 per cent of our ‘water footprint’ comes from overseas, and so it seems that the water issues of the rest of the world are also ours – at least if we want to wear clothes, read books and eat imported foods.

The World Water Week site has info about the water footprint of various products – a cup of tea requires 30 litres of water, whereas a cup of coffee uses up to 140 litres of water. Will you trade your cappuccino for a darjeeling instead? Organisations like Waterwise are calling for a labeling system on goods to show how much water is embedded in them, letting consumers make informed choices.

This might sound far-fetched but just the other day I noticed that the loo roll I’d bought listed the carbon footprint of each sheet, so who knows what the future holds. We’re used to water, water everywhere, but maybe we shouldn’t take it for granted. n