ok back to the thread topic....
A map of water quality around the world....
The US is doing pretty good....but years ago that wasn't the case...we had to do lots of fixing to get things to where they are today.
Water quality information - Standard U.S. Water Treatment Techniques in the 1960's | APEC Water
"By the late 1960s it became apparent that the aesthetic problems, pathogens, and chemicals identified by the Public Health Service were not the only drinking water quality concerns. Industrial and agricultural advances and the creation of new man-made chemicals also had negative impacts on the environment and public health. Many of these new chemicals were finding their way into water supplies through factory discharges, street and farm field runoff, and leaking underground storage and disposal tanks. Although treatment techniques such as aeration, flocculation, and granular activated carbon adsorption (for removal of organic contaminants) existed at the time, they were either underutilized by water systems or ineffective at removing some new contaminants. Health concerns spurred the federal government to conduct several studies on the nation's drinking water supply.
One of the most telling was a water system survey conducted by the Public Health Service in 1969 which showed that
only 60 percent of the systems surveyed delivered water that met all the Public Health Service standards. Over half of the treatment facilities surveyed had major deficiencies involving disinfection, clarification, or pressure in the distribution system (the pipes that carry Many water treatment plants filter their water. Water from the treatment plant to buildings), or combinations of these deficiencies. Small systems, especially those with fewer than 500 customers, had the most deficiencies.
A study in 1972 found 36 chemicals in treated water taken from treatment plants that drew water from the Mississippi River in Louisiana. As a result of these and other studies,
new legislative proposals for a federal safe drinking water law were introduced and debated in Congress in 1973."