Whenever any well, spring or other water supply is suspected of being polluted by sewage or other matter dangerous to health, the health officer of the town where it is located may cause an analysis of the water to be made by a competent chemist, without expense to the owner. If the analysis shows the water to be unfit for drinking purposes they may, with the approval of the department, prohibit its use, and, if it be from a well, may cause the well to be closed.