Lab or Field Testing for Chloramine Residual?

States typically require field analysis for total chlorine residual because the loss of a residual can be significant during sample transport and storage. Despite this, by adhering to the steps discussed in this article, water utilities providing a total chlorine residual in the form of chloramines can demonstrate that tap water samples can be analyzed in the laboratory rather than the field. A free chlorine residual is more sensitive to factors that promote its decay, which makes it difficult, if not impossible, to demonstrate that samples with a free chlorine residual can be collected and returned to a laboratory for total chlorine residual testing. The article includes a table summarizing the results of various experiments comparing new and used sample bottles, and gives tips on helping prevent decay of chloramine residual during sample transport and storage.