Should your Water Management Plan (WMP) Program Team decide to utilize environmental water sampling to validate the effectiveness of the WMP, ANSI/ASHRAE 188-2018 advises that these tests should be performed by a laboratory accredited to a nationally or internationally recognized standard (e.g., ISO/IEC 17025:2017), with Legionellaa included in the laboratory’s scope of accreditation.
Before environmental sampling is undertaken, a Sampling Plan should be formulated. This plan should list the devices and Points of Use (POUs) to be sampled, at what frequency sampling will be performed, what the acceptable control limits will be, and what the response protocol will be for any sample result(s) falling outside of the previously-established control limits.
Calculating Parts Per Million
The phrase “Part Per Million” is a term we use to describe very small amounts of something in a much larger amount of something else. Here are some examples of one part of something in a million parts:
What's required and what is my sampling plan?
The simple answer is no (not directly), and here’s why: There is no known safe level of Legionella in a building water system. Therefore, even a non-detect sample result is not necessarily “safe.” The reason why is because the life cycle of this organism, coupled with the stresses put on it via temperature, disinfectants, etc. found within building water systems, may cause it to enter a viable but non-culturable (VBNC) state.
What You Need to Know
Chlorine and bromine based biocides are widely used for microbiological control in cooling tower systems. These halogen compounds form strong oxidizing agents in water, which is how they kill bacteria and other microorganisms. Routine testing is important to confirm effective halogen residuals are maintained. Low residuals can result in poor microbiological control. High residuals can cause corrosion and destroy inhibitors.
Chem-Aqua representatives are frequently asked, “How often do I need to test my water?” The answer to this question is as varied as the systems that Chem-Aqua treats. There are a number of factors that go into determining the “best practice” for each facility. Typically, these factors are: