CITY OF ROCKWALL 0.486500
ROCKWALL COUNTY 0.350000
ROCKWALL ISD 1.470000
The city of Heath is 0.343300 so their total is even lower at 2.16
Other cities around it such as Fate and Royse City have a MUD of .75 added but doesn't apply to this question.
She asked about Rockwall and Heath, not other areas. If I am wrong please let me know where you got the information so I can correct my records.