Cities are prohibited from constructing water and sewer projects for private purposes. Such purposes include any commercial project, commercial subdivision, private residence, or privately owned residential subdivision. It also includes constructing individual water and sewer lines beyond a meter that measures service or on private property where the municipality does not have an easement. But municipalities may do sewer work on private property when there is excessive inflow from rainwater or groundwater that causes overflows and creates health issues, and the owner agrees to hold the municipality harmless. T.C.A. § 7-35-401.