Idaho Code § 42-3238
Notwithstanding any other provision of law, no water district, sewer district or water and sewer district shall levy or collect any tax, any fee or any other charge of any kind related in any way to the collection or treatment of sewage by such district against any property located in such district which property is served by a private community sewer system. Said properties shall be exempt from any such tax, fee or charge. A "private community sewer system" means a system which collects and processes sewage for ten (10) or more residences, commercial or industrial facilities. The exemption provided in this section shall not apply to residences, commercial or industrial facilities served by an individual septic system. Nothing contained herein shall prohibit a charge for the delivery or furnishing of water by such district.
Idaho Code § 42-3238