The Senate will consider more than a dozen amendments this week that could change how the federal government regulates a class of potentially toxic chemicals that have seeped into groundwater supplies across the country.

Among the amendments are several that would require the Environmental Protection Agency to set nationwide standards for per- and polyfluoroalkyl substances, or PFAS. Another would call for a survey of bodies of water to ascertain the extent of the contamination.

The EPA has already done some initial work on regulating PFAS chemicals, such as setting an advisory limit for drinking water, but many...