"Before treatment, Westport's water tested up to four times state and federal limits. After treatment, it's safe for the children, teachers and staff to drink."
This does not point to a specific limit such as Maxiumum Contanminant Level (MCL) or Maximum Contaminant Limit Goal (MCLG). MCLG is a non-legally binding limit, which is as it states is a goal. MCLG for urainum contaminants is 0 ug/L. Any measurement of any drinking water will always have more uranium than this limit. The MCL is 30ug/L for uranium.
Additionally, the EPA has changed the way in which they have approached limits, previously they quoted something like the World Health Organization limits [3], which are average daily consumption limits. Average implies that some measurements could be high or low. WHO estimates natural concentration of uranium in drinking water is 0.08 ug/L (0.001 Bq/L), which is obviously above the EPAs MCLG.
WHO is a much better resource for information on these limits, and the EPA appears to just take their limits and do a divide by ten.
[1] https://en.wikipedia.org/wiki/Maximum_Contaminant_Level [2] https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=30006644.txt [3] https://apps.who.int/iris/bitstream/handle/10665/272995/9789...