According to the January 22, 2002 final Arsenic Rule, all systems have 5 years to achieve compliance. Exemptions for an additional 3 years can be made available to qualified systems. For those qualified systems serving 3,300 persons or less, up to 3 additional 2-year extensions to the exemption are possible, for a total exemption duration of 9 years. When added to the 5 years provided for compliance by the rule, this allows up to 14 years for small systems serving up to 3,300 people to achieve compliance (66 FR 6976, 6988; January 22, 2001).
Additional information on arsenic is available at http://water.epa.gov/lawsregs/rulesregs/sdwa/arsenic/index.cfm