Frequent Questions

I am attempting to find some literature that discusses acceptable ranges of water age for small to mid-sized utilities. Does EPA have any information on this topic?

This is a complex question to answer because the deterioration of water quality resulting from water age depends on a lot of factors.  Some of these factors include the amount of disinfectant residual, the type of disinfectant residual, the amount of organic matter (which may deplete the residuals), the type of pipe and other material (e.g., iron pipes would be expected to deplete residuals faster than plastic pipes), the water temperature, the age of the system components, the amount of biofilm in the system (all systems have some), and flow patterns in the system. There are many other factors as well.  At best, I would say that it’s a system by system basis, but even this can vary with the time of the year, opening and closing of valves, and other considerations.

I think the following link may provide some useful information, because it provides information on some of these factors.  However, it doesn’t get into all of them.

http://www.epa.gov/sites/production/files/2015-09/documents/2007_05_18_disinfection_tcr_whitepaper_tcr_waterdistribution.pdftors

In addition, I would suggest guidance manuals on disinfection byproducts.  Since water age can impact their formation the guidance manuals should have some useful information.

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