(a) The furnishing of sewer and garbage service in conjunction with the water services by the authority as well as the furnishing of water services are hereby declared to be a governmental function.
(b) The authority shall not be liable for any tort, whether negligent or willful, committed by any director, agent, servant, or employee of the authority in the furnishing of water service or in the construction, maintenance, or operation of any water or sewer or garbage facilities.