Agricultural Pollutants accounted for 24% of the contaminants, Urban Pollutants accounted for 17% of the contaminants, Industrial Pollutants were by far the worst and accounted for 47% of the contaminants, and finally 12% of the contaminants were from water treatment pollutants (some of the same chemicals used to try and remove the other contaminants).
Further, the study shows that 40 of the contaminants were delivered to 1 million or more customers via the taps in their homes. The EWG collected multiple samples from the individual State water offices, which collect it from their public utilities as a part of their responsibility as primary enforcement agents. The Environmental Protection Agencey (EPA) does not maintain a national tap water database instead they rely on the sporadically collected samples from the States and draw conclusions from there. This study by the EWG (www.ewg.org) is one that we should all be familiar with as it clearly defines for us what's coming out of our taps... Cheers!