An adult American drinks from one and a half to five or more quarts of water a day. His total daily intake depends on climate, workload, body size, and many other factors.

Most of us think that the water we drink is safe. It usually is, but some of us are using poorly treated drinking water which has been spoiled by bacteria, toxic chemicals, metal, and a possible wide range of other pollutants.

At least 4,000 cases of water-borne illnesses occur each year in this country. The actual total may be ten times greater. Further, medical science has not yet determined the effects on man of long-term, low-level exposure to contaminated drinking water.

Q. Underline the sentence which contains frightening statistical facts.