The availability of drinking water, per person, is shrinking, due to the growth of the world’s population, as well as other factors. This issue can be addressed by increasing production, better distribution and through less waste of fresh, drinking water. Reducing waste by using drinking water only for human consumption, is another option. In some cities, such as Hong Kong, sea water is used for flushing toilets all over the city, in order to conserve fresh water resources.