China will face a water supply deficit of up to 201 billion cubic meters in the next two decades if the country does not adopt proper water-saving technologies and practices, a report by global management consulting firm McKinsey & Company has found.

Given the drastic growth in industrial and municipal water use, China's total water demand could reach 818 billion cu m by 2030, but the supply would stay at only 619 billion cu m, the report estimates.

But the country has enough solutions to close the gap, and most of them are affordable and profitable, said Martin Joerss, a partner at McKinsey & Company who led the study.

The report identifies 55 solutions to boost water supply and conserve consumption in agricultural, industrial and municipal sectors.

"China has a 'double opportunity' for both the government and private sectors," said Joerss, adding that investing in water-saving technologies and operations can not only help solve the water crisis, but also bring good economic returns.

"Some of the solutions need significant investment, but most of the solutions we examined represent attractive investment opportunities for the private sector," Joerss said.

Investing in 47 solutions, such as building more sophisticated irrigation systems, reusing industrial water and patching up leaky municipal water pipes, could generate an annual profit of 131 billion yuan, the report finds.

Water-intensive industrial sectors, such as thermal power, textiles, paper, iron and steel, have the most potential for water conservation, Joerss said.

"China already has a very high standard on energy efficiency, for example in the iron and steel industry, but the country should also emphasize water-efficient technologies in the future five-year plans."

China is suffering a severe water scarcity as its population of 1.3 billion - one-fifth of the world's total - relies on only 7 percent of the global freshwater resources.

Right now, water pollution and scarcity is costing China 2.3 percent of its gross domestic product every year, according to the report.

The study also found that eight out of 10 of China's water basins could face acute supply shortages by 2030, with the worst in Haihe river basin in North China.

Groundwater in north China is already overexploited by 120 billion cu m, Xiaoxiang Morning News reported last week, citing earlier official statements.