CONCORD, N.H. — Several lawmakers are calling on a plastics company believed to be source of tainted drinking water in New Hampshire to connect 100 properties to the public water system.

The legislators wrote this week to state environmental officials asking that Saint-Gobain Performance Plastics connect the Bedford families to the Manchester Water Works.

The company agreed to fund design efforts for a potential extension of public water service into Bedford after wells near the plant were found to contain a toxic chemical linked to cancer and other illnesses above state standards. If approved by month’s end, the company said construction could begin on the extension by the end of the year.

Since last year, perfluorinated chemicals or PFCs have been found in the drinking water at 222 sites across the state.