Sorry, but I'm not understanding how that can be illegal. The tapped line generates usage on the meter of the main line, which determines the amount of the bill for water usage for both residences; the bills have been paid in full and are current. How can this be illegal? It's not like you were getting "free" water, as the meter reads the combined usage. Was a permit required to tap the line? Does the water company prohibit line tapping that was authorized by the primary holder of the account? Do you and/or your mother currently own the property?