The Bedford Regional Water Authority is developing a policy of prevention and response, after a number of sewer backups recently into homes in the town of Bedford. The BRWA board, on Tuesday, assigned its policies and projects committee to look into how to prevent backups. The authority’s systems director says the problem likely comes from roots reaching through old concrete pipes and causing clogs in the line. Heavy rains send storm water through cracks or joints, and when the extra load combined with the normal sewage reaches a clog, it backs up into homes. The Board members discussed the possibility of setting aside money to pay for cleanup to varying degrees.