Australia's fifth-largest city could be reliant on bottled water as early as next week as overuse and drought stretch the Murray river to its limit

The water in Australia's biggest river is running so low and is so salty that the nation's fifth-largest city, Adelaide, is at risk of having to ship water in to its residents, politicians have warned.

Adelaide's water crisis follows similar problems in cities around the world, as the combination of growing population, increasing agricultural use and global warming stretches resources to the limit. Experts are warning of permanent drought in many regions.

Salinity levels in some stretches of the Murray river already exceed the World Health Organisation's (WHO) recommendations for safe drinking, and South Australia's water authority and 11 rural townships east of Adelaide have been told to prepare for the worst.

"Another dry year will deplete our reservoirs and the water in the Murray will become too saline to drink. We are talking about 1.3 million people, who are not far off becoming reliant on bottled water. We are talking a national emergency," said South Australian MP David Winderlich.

As early as next week, water from parts of the river may become too dangerous to drink, which would require the water authority to begin delivering supplies to hospitals, clinics, aged care facilities and local supermarkets in plastic bottles, said Winderlich.

"There's simply too many people pulling water out of the river," said Roger Strother, Coorong council mayor. "We've been saying that one day it would catch up, and this summer is when it is going to happen. It could be next week."

Recent rains have topped up Adelaide's dams, but only enough for one year, and the Murray-Darling Basin Authority, which oversees water use across the whole of south-east Australia, says water levels in reservoirs are much lower than expected. Today the authority said the whole basin was at 25% capacity.

Australia's worst drought in a century has lasted over 10 years in places, and many cities have had to restrict water use.

Climate experts fear the continent faces a permanently drier future as the impact of global warming kicks in. South Australians have watched the waters stagnate as farmers, especially cotton and rice growers upstream, siphoned up to 83% of the water from the river system.

The WHO says the acceptable level of salinity for safe drinking water is 800 EC (electrical conductivity) units but the salinity in parts of the Murray is now around 1,200 EC units. The water authority says it will begin shipping water when the salinity rises to 1,400 EC units.

Adelaide is one of many cities around the world facing acute water shortages as populations grow, long-term droughts continue and ground water is not replenished. The Chinese water minister, Chen Lei, today told engineers at a water conference that two-thirds of Chinese cities now face serious shortages due to rapid industrialisation and climate change.

"Compared to 1956-79, the average rainfall has dropped 6% in three major river basins," Lei said. "Most parts in the north of China are now facing water shortages problems, especially because of the increasing influence of climate change and the faster speed of industrialisation and urbanisation."

By 2015, Lei said, water efficiency would have to be increased by 30%. "Water abstraction must be strictly controlled. We should have strict management of groundwater exploitation and consumption, put a limit on total use of groundwater, and ban or set quotas on groundwater exploitation. Nearly two out of three cities are facing water shortages, and the farmland affected by drought reaches nearly 15m sq km a year."

According to a new UN environment programme report, perennial drought conditions are developing in south-eastern Australia and south-western North America. "Projections suggest that persistent water scarcity will increase in a number of regions in coming years, including southern and northern Africa, the Mediterranean, much of the Middle East, a broad band in central Asia and the Indian subcontinent," the report said.

"There is growing concern that thresholds or tipping points may now be reached in a matter of years or a few decades, including dramatic changes to the Indian subcontinent's monsoon rains, the Sahara and west Africa monsoons, and climate systems affecting the Amazon rainforest," it said.

Hopes in some countries that an El Niño weather event would bring rain to parched areas of the US this week declined as the US government climate prediction centre said temperatures in the equatorial Pacific had stopped climbing. During strong El Niños, abnormally warm waters in that region pump heat and moisture into the atmosphere, which leads to intense storms.

Cities around the world under water stress



Beijing: Most of Beijing's water comes from the Miyun reservoir, but a decade of drought and huge population increase has left extreme shortages. Water diversion projects are helping, but this is depleting resources from other regions. The city must spend $3.5bn (£2.2bn) in the next five years to cope with a population expected to rise to 17 million.

Nairobi: The city has imposed water rationing, following an acute drought that has affected all Kenya's water catchment areas. River and reservoirs are at historically low levels. Flower farms and export-oriented agriculture are also reducing supplies available to people.

Mexico City: 2009 has been the driest year recorded in the city of 19 million people. Water is rationed and many areas have no piped water for days at a time. The government has imposed fines of up to $1,200 for hosing down cars and sidewalks or watering lawns during daytime hours. Signs warn that the city could run out of water next spring unless residents switch to low-flow showers and toilets, and plug leaks.

Gaza: Water fit for human use will run out in the Gaza strip within 10 years, the Gaza Coastal Municipal Water Utility and UN agencies said this month. Tap water is already salty, and only 5-10% of groundwater is drinkable. Gaza's population is expected to increase to 3 million by 2025.

Kathmandu: Erratic rainfall and drier winters have left Nepal's capital very short of water. The water company can provide only 160m litres a day but the demand is well over 200m litres. Many households are drilling their own boreholes to extract groundwater with electric pumps, but the water table is sinking approximately 2.5 metres a year and this is not sustainable in the medium term.