Monday, June 18, 2007

Without Water - No Life

Water is not just only an amazing chemical (H2O) it is the lifeblood of our planet earth. Population growth and development have polluted and depleted the world’s water supply – experts say the wars of the 21st Century will be fought over oil and water. Every eight seconds a child dies from drinking contaminated water. World demand for water is doubling every 21 years. With deforestation, draining wetlands and sealing more and more of the earth’s surface, we have halved the hydrological cycle of water. There is less groundwater recharge through rapid run-off and also less infiltration of rainwater due to warmer earth surfaces (global warming).

Excessively fast re-evaporation through more and more irrigation in agriculture leads to salination, causing salt build-up on huge tracts of land like in Australia and other dry parts of the globe. Water use in agriculture is very high in some foods, especially in meat production. Each calorie of meat takes far more water than a calorie of grain: approx. 1,000 litres H2O for a kg of wheat, 2,000 litres for white rice, but 50,000 litres for 1 kg of beefsteak, 500 litres for a litre of milk, over 200 litres in a litre of wine. Cotton is worse, 5,000 litres for a kg. (source: Forbes Magazine).

So how are we doing in New Zealand? Luckily in some parts of our land we have plenty of water, but parts of the East Coast of the North Island, Otago, Canterbury and Marlborough have a serious shortage of water, especially in El Nino years.

We have to change our water use to more sustainable levels. Agriculture and tourism are the biggest users of water. Industrial and domestic use is also very high in the developed world The flush toilet uses the most and in future it will be unsustainable to use drinking water to transport faeces and urine, so composting or dry toilets will be used more often where suitable.

Grey water should be re-used. In Singapore, for example, sewerage is turned into drinking water with high tech cleaning systems.

But fresh, clean water is a non-negotiable human right: it is the liquid currency of survival

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