§ 150.681 LANDSCAPE WATER CONSERVATION STANDARDS.
   (A)   Dedicated landscape water meter and backflow device.
      (1)   Separate water meters shall be required for all new landscaping or renovated landscaped areas that have a construction area of new landscaping larger than 5,000 square feet.
      (2)   All irrigation systems must have a backflow device as required by the Texas Commission on Environmental Quality.
   (B)   Landscape water budget. The landscape water budget for new landscape shall be no more than 70% of reference evapotranspiration per square foot of landscaped area, including turf grass. The landscape water budget shall be calculated using the equation below:
      (1)   Landscape water budget = (0.7)(ETo)(0.00083)(LA);
         (a)   Water budget =annual upper limit of irrigation water allowed. (CCF/year);
         (b)   0.7=ET adjustment factor;
         (c)   ETo=Reference evapotranspiration;
         (d)   Conversion factor to CCF;
         (e)   LA=Landscape area (square feet).
      (2)   New landscapes that are irrigated with non-potable water are allowed a total of 100% of evapotranspiration rate per square foot. Acceptable alternatives for non-potable water can be found in § 150.688.
      (3)   The annual water use shall not exceed the annual water budget.