GEF

Unit 3  |  Water Use and Human Water Systems 81 Water testing and monitoring can reduce the risk of waterborne disease outbreaks. Other domestic water quality issues have recently gained attention. A percentage of pharmaceuticals ingested by people are not absorbed by the body, but are excreted into the sewer system and make their way into surface or groundwa- ter sources. Because conventional water treatment does not remove these chemicals, they eventually turn up in household water. Among other substances, caffeine, artificial hormones, and anti-seizure medication have been discovered in the U.S. drinking water supply. The problem is not restricted to the U.S., as tests have revealed trace amounts of prescription medication in the water systems of Canada, Australia, and other countries. While concentra- tions of these chemicals are extremely low, scientists and the general public are increasingly concerned that they may have negative effects on human health and on ecosystems. This growing problem highlights the interconnections between humans and natural systems. Another growing problem in the developed world is aging water infrastructure. In many cities in the U.S. and Europe, water infrastructure first installed in the early decades of the