August 2023

Purified water is a critical ingredient in any aqueous personal care product. In a manufacturing environment, it’s needed at a large scale and interruptions to supply can have major effects on production.

Well designed and maintained reverse osmosis and/or deionization systems will reliably extract metals, minerals, solvents, pesticides, and other impurities from municipal water, but what about the microbiological quality of the water?

Typical water filtration systems are not designed to remove microorganisms, and that matters because preservative systems can be overwhelmed by heavy microbiological contamination from water.

Microbial populations in production water treatment systems are controlled by the main factors listed below:

• Microbiological quality of the input water. Control over this element is often limited, though some manufacturers can choose well or municipal water. Municipal water generally has low, consistent inbound microbial counts but it may vary seasonally.
• Water filter substrates. Water filter substrates (the filters themselves) can serve as food sources for bacteria. If water is not sufficiently de-mineralized by the treatment system, massive microbial populations can take hold, almost always as biofilms on the surfaces of filters. Some water filter substrates are treated with antimicrobial agents to prevent this.
• Water filter replacement frequency. The regular changing of water filters ensures filtration efficacy and dramatically decreases the odds of biofilm formation and microbial population generation within the system.
• Water storage duration and tank cleaning. Generally speaking, the longer water is stored the higher the microbial content will be. If the water stored in tanks is not absolutely pure, the tanks will grow biofilms over time, easily detected by a slimy feel on underwater surfaces. Regular cleaning helps control microbial growth in water storage tanks.
• Waterline size and length. Smaller water lines are generally better than larger ones from a microbial perspective because there is less surface area and more sheer force to continually flush off microbial populations on the nearly-impossible-to-clean inside surfaces of pipes.
• Presence of “dead legs.” Plumbing circuits that are shut off at certain points in time are notorious reservoirs of microorganisms in water systems, as are capped or stubbed pipes where water cannot flow. So-called “dead legs” should be avoided, or flushed regularly to control microbial populations.
• Presence of disinfection systems, such as ozone or UV. Ozone or UV light systems are a reliable means to disinfect production water, but should be used as a fail-safe, not the primary tool to fight microbial contamination within the system.
• Condition and use of water sampling ports. Water sampling ports should be clean, narrow in gauge, short, and also flushed at least 30 seconds before collecting production water samples. It is possible to have a great water system and great water, but contaminated sampling ports that give the false appearance of a water system problem.

Measuring the microbiological purity of a production water system is easy and relatively inexpensive. Water samples are simply collected and shipped to the lab on ice for routine plating. This provides a snapshot of microbial populations in time. After several weeks of sampling, a clear picture of water filtration system microbial populations will emerge, then trends or changes can be easily seen thereafter.

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