Ohio Rev. Code § 743.09
No charge shall be made by a municipal corporation or the water-works department thereof for supplying water for extinguishing fire, cleaning fire apparatus, or for furnishing or supplying connections with fire hydrants, and keeping them in repair for fire department purposes, for the cleaning of market houses, or the use of any public building belonging to the municipal corporation.
In any case in which a school district includes territory not within the boundaries of the municipal corporation, a proportionate charge for water service shall be made in the ratio which the tax valuation of the property outside the municipal corporation bears to the tax valuation of all the property within such school district, subject to the rules and regulations of the water-works department of the municipal corporation governing, controlling, and regulating the use of water consumed.
R.C. §743.09