We have a good German friend who speaks very good Chinese. She travels around China frequently for business and meets with many local Chinese business partners. The first year she came to China, she kept asking for cold water at business meetings. But inevitably, she would get either boiling water or green tea back as a drink.
There is a two-fold reason for that:
First, most Chinese would not serve plain water to their guests because it is seen as too simple and too bland (only family members are offered plain water).
Second, cold drinking water is not always available. Before the days of bottled water, most people in China obtain cold water by boiling tap water (not portable in China) first, and then let it cool to room temperature. Although in recent years, more and more people began to drink bottled mineral water, in smaller towns and provincial places, bottled water is still considered a luxury item. When guests come, they are accustomed to serve hot tea using boiled tap water. When the guests don't drink tea, they can only offer them hot boiled water as an alternative.
Over the years, our friend tells us that she no longer asks for cold water at Chinese business meetings. In fact, she now finds herself pouring hot water into her mug even when she works alone in her office. That, she says, is a sign that she's finally settled here.
(selected from 101 Stories for Foreigners to Understand Chinese People by Yi S. Ellis and Bryan D. Ellis, published by China Intercontinental Press in 2012)