Drinking water Technology, Eawag, developed a method by which hazard maps could be produced for geogenic toxic substances in groundwater. This provides an efficient way of determining which wells should be tested. Parameters for drinking water quality typically fall within three categories: Physical and chemical parameters include heavy metals, trace organic compounds, total suspended solids (TSS), and turbidity. Microbiological parameters include Coliform bacteria, "E. coli", and specific pathogenic species of bacteria (such as cholera-causing "Vibrio cholerae"), viruses, and protozoan parasites. Chemical parameters tend to pose more of a chronic health risk through buildup of heavy metals although some components like nitrates/nitrites and
Reuse of bottles contain the chemical Bisphenol A (BPA), which is made from polycarbonate and which shares resin identification code 7 with other plastics. Another chemical found in plastic drinking bottles is phthalate. Both of these chemicals are controversial because they are known endocrine disruptors, which can interfere with the body's hormonal system. A study by the Harvard School of Public Health (HSPH) found that participants who drank from polycarbonate bottles – which is the plastic commonly used in disposable plastic water bottles, other plastic drinking bottles, and baby bottles – for just one week showed a two-thirds increase in their urine of