Rodman was in town to celebrate the 80th anniversary of Black & Veatch's business in Hong Kong. In 1930, the Missouri-based company helped the government to design and build the Shing Mun Reservoir, which boosted the local supply of fresh water after a severe drought forced 60,000 people to leave the city.

Since then, Black & Veatch has had a hand in almost every major piece of water infrastructure in Hong Kong, from the massive High Island and Plover Cove reservoirs to underground storage tanks and an overhaul of the city's ageing water pipes.

But for all Hong Kong's technological prowess, it lags behind in conservation. People in Hong Kong are water hogs by any measure. Data from the International Water Association shows that the city's water footprint - which takes into account direct and indirect consumption - is 219 litres per person, per day; a higher rate than nearly every other city in the world.

According to the Water Supplies Department, domestic fresh water consumption increased from 493 million cubic metres of water in 2004 to 519 million in 2008.

Close to 80 per cent of Hong Kong's water comes from the Dongjiang in Guangdong , which also supplies water to more than 30 million other people in Guangzhou , Dongguan and Shenzhen .

'Although we don't have many water resources, we've been able to rely on Dongjiang water for so many years, we have forgotten about the problems,' said David Chen Yong-qin, chairman of the Chinese University of Hong Kong's geography and resource management department.

As Hong Kong's mainland neighbours increase in size and wealth, so will their demand for water. Meanwhile, climate change will make rainfall patterns more unpredictable, leading to an ongoing drought that could cause water levels in the Dongjiang basin to decrease. 'Competition for water will increase,' said Chen. 'We need to take conservation more seriously.'

Part of that will involve understanding something that water experts call 'the nexus of water and energy'. The amount of water each person consumes goes well beyond an evening shower or a load of laundry. Production of a single kilogram of beef requires 15,000 litres of fresh water and each litre of fresh water consumes energy through treatment and transportation.

When cities and countries become more populous and more prosperous, their fresh water consumption increases, regardless of the amount of water available nearby. 'How are we going to spread that fresh water out?' asked Rodman.

One answer is new technology - even something as simple as Hong Kong's dual pipe system, which allows toilets to be flushed using seawater instead of fresh water and saves 270 million cubic metres of fresh water every year. Black & Veatch is currently rehabilitating 3,000 kilometres of water pipes, which will prevent water from being wasted through leaks and bursts. But it comes at a price. Building the new infrastructure required to cope with the world's increasing demand for fresh water could cost US$40 trillion, said Rodman.

'You have to ask, where will money come from?' In the long run, he said, limiting demand will be much more cost-effective than increasing supply.

Two years ago, the government introduced the Total Water Management programme, which emphasises water conservation through education and upgrading Hong Kong's water infrastructure. One of the programme's initiatives is a water efficiency labelling scheme for consumer products.

So far, though, there has been no sign that consumers are concerned enough about water conservation to actually change their habits. Part of the reason is that, even as the government encourages conservation, political pressure has kept water rates frozen for 15 years. In the 2008-09 financial year, the government earned HK$2.587 billion in water rate revenue, while the cost of buying water from Guangdong was HK$2.621 billion. As a result, there is little political motivation to raise rates to cover the cost of both supplying Hong Kong with water and maintaining its infrastructure.

In a paper presented by the Legislative Council Panel on Development last May, the government acknowledged Hong Kong's low water rates contributed to its exceptionally high rate of water consumption. 'We do not rule out the option of changing the water tariff structure to induce a reduction in consumption,' it said.

Until that happens, said Chen, Hong Kong might continue to struggle with conservation. 'The water bill is always the smallest one,' he said. 'But this is a problem worldwide. Water is really cheap and its price doesn't reflect its economic value, or the costs of diverting the water, treating it and distributing it.'

On tap

Hong Kong's water footprint is higher than that of nearly every other city in the world

Domestic consumption is rising - in 2008, this many cubic metres were used: 519m