Bulk Reaction Coefficient for water modeling

[SonomaEng]

I have been struggling with a problem on how to model a small water distribution pipe. Specifically, what is a good starting point for the bulk reaction coefficient and why is it so hard to find information on this factor when it appears to be a very important factor in hydraulic modeling?

I am connecting to an existing water distribution system that pulls groundwater nearby. My connection point is directly outside of the chlorination shed the pipe must travel appox. 1400 feet where it will connect to three houses and possible a fire hydrant. While reading the user manual for EPAnet it says to use a value of 1 for the bulk reaction coefficient. In order to provide adequate fire flow I need an ID of about 6.5 inches. When using this size pipe and a bulk reaction coefficient of 1 I maintain a residual chlorine of 0.22 mg/L at the minimum daily use of 1 gpm. (I have found some decent resources but I wouldn't mind some tips on determining the minimum/maximum uses, the current houses have no record data of water use to go by)

I am not confident in giving the ok to build this pipeline with a 6.5" pipe to provide fire flow to the houses and then find out that the value of 1 was way off and the residual cannot be maintained.

Any hope on how one would normally go about this issue when starting a modeling project.

Thanks,

Mike