Aquiarion Water Company has proposed a million gallon storage tank off Old Green Road in Newtown.  The Newtown Planning and Zoning Commission has held two public hearings on the proposal, which the company says is needed to improve the reliability of the public water supply.  The concrete tank would stand 50 feet tall and be 62 feet wide. A special zoning permit and a site development plan are required for approval.  Aquarion intends to buy the 5 acre lot if approval is given.