In many parts of the world, water, ice, and even some bottled water can be hazardous. To reduce the chance of contracting water-borne diseases, advise travelers to drink only water from bottles with intact seals. They should also use bottled water to brush their teeth or rinse their mouths and contact lenses. Travelers should also be wary of ice cubes, fruit juices, and iced tea, which may be made out of or diluted with contaminated water. Finally, individuals need to keep in mind that the alcohol in liquor will not kill bacteria.
Water can also contain parasites.
Schistosomiasis infection begins when larvae of a flatworm, common to fresh water in many parts of the world, penetrate a person's broken or intact skin and migrate into the portal circulation. Adult worms eventually lodge in the bladder or intestines. Salt water and water treated with chlorine or iodine is safe, but fresh water can be infested. Swimming or bathing in fresh water in rural areas should be avoided. If exposed, immediate and vigorous towel drying, and application of alcohol may reduce risk.