An investigation that found pharmaceuticals in the drinking water of 41 million Americans has sparked concern but the Massachusetts Water Resource Authority said its watersheds are fine.Over the course of a five-month investigation, the Associated Press discovered that drugs, in minute amounts, have been detected in drinking water of 24 metropolitan areas. Boston was not one of the areas tested but the study revealed that Boston also doesn’t test for pharmaceuticals in its water.Saugus Department of Public Works Superintendent Joseph Attubato said that thought does not concern him. Attubato said he is confident that the MWRA’s water supply is clean.”I felt comfortable with it all along to be honest because they do excessive work up there,” he said. “I think the Quabbin is one of the best reservoirs in the country probably.”And so does the MWRA.In a memo sent out to each district, MWRA Distribution System Liaison Andrea Enos wrote, “in a nutshell, we do not believe we have a problem with pharmaceuticals in our drinking water.”Enos said the MWRA’s watersheds are protected and there are not wastewater treatment plants within the watersheds, “so it is highly unlikely for the pharmaceuticals to enter the water system.”In 2005, the MWRA began treating water by using an “ozonation system,” which Enos said the scientific community believes is the most effective treatment for drinking water.”While MWRA does not expect that tests will show any pharmaceutical compounds in its source water, it is reassuring that recent research indicates that the type of ozone disinfection process currently being used by MWRA is effective at oxidizing and destroying these types of compounds,” read a full statement made earlier by the MWRA.Attubato said he feels completely comfortable with the MWRA’s statement.”We’re OK,” he said. “I’m just not concerned or worried at all.”