Drinking water (or potable water) is water safe enough to be consumed by humans or used with low risk of immediate or long term harm. In most developed countries, the tap water supplied to households, commerce and industry meets the water quality potability standards, even though only a very small proportion is actually consumed or used in food preparation. Other typical uses include washing, toilets, and irrigation; greywater provides an alternative to the latter two. Over large parts of the world, humans have inadequate access to potable water and use sources contaminated with disease vectors, pathogens or unacceptable levels of toxins or suspended solids. Drinking or using such water in food preparation leads to widespread acute and chronic illnesses and is a major cause of death and suffering worldwide in many different countries. Reduction of waterborne diseases and development of safe water resources is a major public health goal in developing countries. Water has always been an important and life-sustaining drink to humans and is essential to the survival of most other organisms. Excluding fat, water composes approximately 70% of the human body by mass. It is a crucial component of metabolic processes and serves as a solvent for many bodily solutes. The United States Environmental Protection Agency in risk assessment calculations previously assumed that the average American adult ingests 2.0 litres per day. However, the United States Environmental Protection Agency now suggests that either science-based age-specific ranges or an all ages level (based on National Health and Nutrition Examination Survey 2003-2006 data) be used. Bottled water is sold for public consumption in most habitated parts of the world. The word potable came into English from the Late Latin potabilis, meaning drinkable.