The California Department of Public Health adopted a new and updated Maximum Contaminant Level (MCL) list in November of 2010. As you look through it, you may notice that there are quite a few compounds on the list that did not previously have MCLs. We commonly substituted the San Francisco Regional Water Quality Control Board (RWQCB) Environmental Screening Levels (ESLs) for those compounds, if necessary. You may also notice that many compounds have lower MCLs than what was listed previously by the California Department of Public Health.
Perhaps most interestingly, 1,4-dioxane, 1,2,3-TCP, NDMA, and Nitrosamines now have notification limits, but do not have MCLs. These notification limits really only pertain to potable water suppliers, but the same values are likely to be the MCLs in the upcoming years.
This is worth keeping an eye on.