It is recommended by the Texas Commission on Environmental Quality (TCEQ) to test your water well each year.  It is recommended that you sample the well water and have it analyzed for fecal coliform, nitrates, and total dissolved solids (TDS) once annually or any time you notice a change in color, taste, or smell of the water or after pump or well maintenance.  Be sure to ask lab officials for instructions on sampling and shipping procedures as some analyses require specific protocol.
Testing should be performed by an accredited lab. Contact Tarrant County for more information on how to retrieve a water well test here.