Upon formation of a water authority or sanitary authority, a city may annex territory situated within the boundaries of the water authority or sanitary authority, but shall not remove any water mains, sewers and drains, service installations, reservoirs, structures, facilities and other improvements or any service provision capability from the water or sanitary authority unless the county governing body or boundary commission determines that:
(1) Withdrawal of the territory or improvements from the water or sanitary authority will have no substantial adverse impact on the ability of the water or sanitary authority to provide service to the remaining territory;
(2) The withdrawal is not solely for the tax advantage of a property owner;
(3) The withdrawal will not result in noncontiguous parcels being served by the water or sanitary authority; and
(4) The water or sanitary authority cannot provide adequate service to the subject territory within a reasonable time.