• Published
  • 341st Missile Wing Public Affairs


Malmstrom Air Force Base
Public Water Supply MT0000515
Haloacetic Acids (HAA5) MCL
1st Quarter 2019


Malmstrom Air Force Base’s water system exceeded the maximum contaminant level (MCL) for Haloacetic Acids (HAA5). This is not an emergency. As our customer, you have a right to know what happened, what you should do, and what we are doing to reduce the HAA5 levels from the water that we purchase from the City of Great Falls.

We are required to monitor your drinking water for specific contaminants on a regular basis. The Stage-2 Disinfection Byproducts Rule maximum level for HAA5 is 60 microgram per liter (ug/L). The test results show that our system exceeded the MCL for HAA5 at 61 ug/L. The MCL is a Locational Running Annual Average (LRAA) which is calculated over the last consecutive four quarters. Our current quarterly reading was 39 ug/L - well below the 60 ug/L standard.

HAA5 concentrations were elevated during the 2nd and 3rd quarters of 2018 perhaps due to organic material from the spring wildfires present in the drinking water. This is the second quarter in a row with this same high HAA5 concentration as part of the LRAA. It is possible that the LRAA may be affected in upcoming quarters, requiring subsequent notices until results are lowered.

What does this mean? What should the customer do?

This is not an emergency. If it had been, you would’ve been notified immediately. However, according to the EPA, “Some people who drink water containing HAA5 in excess of the MCL over many years, may have an increased risk of cancer.” This is based on preliminary animal research and drinking 2 liters of water daily over an average lifespan.

It is not necessary to boil the water or to use an alternate water source. However, if you want to take extra precautions, you can use an activated carbon filter. Please contact your health care professional, if you have specific health concerns.

Steps We Are Taking:

Malmstrom AFB is committed to providing our customers with the highest water quality possible. We are working with the city of Great Falls to identify process changes that may reduce HAA5 concentrations such as water infrastructure upgrades to include a new chemical feed and Ultra Violet systems.

Please share this information with all the other people who drink this water, especially those who may not have received this notice directly. For more information, please contact Bioenvironmental Engineering at 406-731-1580.

PWS ID: MT0000515                                                 Date Distributed: 24 April 2019