The Pre/Postnatal City Water Standard is a more in-depth analysis which includes a more comprehensive scan for heavy metals, minerals, a full volatile organic scan and haloacetic acids. Volatiles are becoming more common contaminants in some city water supplies, the most common being trichloroethylene and tetrachloroethylene.

While the EPA has established limits for these in drinking water they are based upon acceptable risk, so if present you may opt out to reduce any risk and treat the water appropriately.