(Formerly referred to as "Memorandum on Treatment Chemicals as Do Not Drink or Use Guidance".)

Complete documentation: Immediate Action Levels for Water Treatment Plant Chemicals doc format of Immediate Action Levels for WTP Chemicals
pdf format of Immediate Action Levels for WTP Chemicals

In response to a number of incidents at treatment plants for public water supplies resulting in the need for emergency measures to be taken, MassDEP has derived Immediate Action Levels for a number of indicator parameters for commonly used treatment chemicals. These limits are intended for use by plant operators to identify when a situation involving chemical over-feeds or use of the wrong chemical has occurred of sufficient gravity to require the implementation of emergency response procedures. These parameters are frequently and routinely monitored in the treatment plant. In addition to the levels listed below, water delivered to the entry point of the distribution system is also required to meet various other federal and state standards and guidelines (see 2014 Standards & Guidelines for Contaminants in Massachusetts Drinking Water ).

Treatment ChemicalIndicator Chemical / ParameterImmediate Action LevelApplicable to:
Acids, caustics High pH pdf format of Recommended pH Action Level
doc format of Recommended pH Action Level pH levels > 11all
Acids, caustics Low pH pdf format of Recommended pH Action Level
doc format of Recommended pH Action Level pH levels < 4.5all
Sodium fluoride, fluorosilicic acid, sodium fluorosilicate Fluoride pdf format of Recommended Fluoride Action Level
doc format of Recommended Fluoride Action Level 10 mg/Lall
Chlorine, chloramines Free chlorine pdf format of Recommended Action Levels for Free Chlorine
doc format of Recommended Action Levels for Free Chlorine 25 mg/Lall
Chlorine dioxideChlorine dioxide

Recommended Limits for the Disinfectant Chlorine Dioxide doc format of Recommended Chlorine Dioxide Limits
pdf format of Recommended Chlorine Dioxide Limits
2 mg/Lwomen of childbearing age, infants and young children
 72 mg/Lother healthy members of the population
 Chlorite2 mg/Lwomen of childbearing age, infants and young children
 72 mg/Lother healthy members of the population
 pH
free residual chlorine
< 4.5 (low pH)
> 11 (high pH)
25 mg/L (free chlorine)
all
 pH
ORP *
(sample location on chlorine dioxide delivery line)
employ facility-specific limitsall

* ORP = oxidation-reduction potential