Ben Harding asked what were the differences between the AWWARF edition of EPANET (1.5) and the standard edition (1.1e). The AWWARF edition was produced to complement the report "Characterization and Modeling of Chlorine Decay in Distribtuion Systems" which can be purchased from AWWA. It includes the following features, all of which are slated to appear in Version 2 of EPANET:

Bulk reaction orders can be any number (not just first order)
Wall reaction order can be either zero or first-order
Wall reaction coeffs. can be inversely related to Hazen-Williams C-factors
Calibration reports can be produced which list the mean absolute error and root mean square error between predictions and observations, and correlation coefficient between predicted and observed means of any variable.
Pipe roughness coefficient and reaction rate have been added to the list of variables that can be chosen from the Browser to view on the system map.

Lew Rossman