The 1974 Safe Drinking Water Act designated regulation for only 91 chemicals out of approximately 95,000 chemicals with potential to enter the water system.
"They're from 1974 with the Safe Drinking Water Act, which only designated 91 chemicals. 91 out of now what we know is about 95,000 chemicals, rough estimate, that have potential to get into our water system." (said at 0:06:15)
No published record matching the specific claim that the 1974 Safe Drinking Water Act designated regulation for only 91 chemicals out of approximately 95,000 chemicals with potential to enter the water system was located; this does not prove the claim false.
corroborated by web sources
Under the Safe Drinking Water Act of 1974 and its subsequent amendments, the Environmental Protection Agency has established enforceable standards for over 90 drinking water contaminants, compared to roughly 85,000 to 95,000 chemicals in commercial use.
epa.govwaterquality-hub.comchasechewning.commariashriversundaypaper.com