The following are exempted from taxes imposed by this chapter:
(1) rainwater harvesting equipment or supplies, water recycling and reuse equipment or supplies, or other equipment, services, or supplies used solely to reduce or eliminate water use;
(2) equipment, services, or supplies used solely for desalination of surface water or groundwater;
(3) equipment, services, or supplies used solely for brush control designed to enhance the availability of water;
(4) equipment, services, or supplies used solely for precipitation enhancement;
(5) equipment, services, or supplies used solely to construct or operate a water or wastewater system certified by the Texas Commission on Environmental Quality as a regional system;
(6) equipment, services, or supplies used solely to construct or operate a water supply or wastewater system by a private entity as a public-private partnership as certified by the political subdivision that is a party to the project; and
(7) tangible personal property specifically used to process, reuse, or recycle wastewater that will be used in fracturing work performed at an oil or gas well.