Point-of-Use Filters for Control of Microorganisms in Building Water Systems: 5 Things You Should Know

Author: Stephen Betts - Water Safety Group Representative

Point of Use Microorganism Control
Building water systems can be the source of illnesses such as Legionnaires’ disease and others caused by waterborne pathogens.  Point-of-Use (POU) filters can play an important role in managing this risk, and may be a valuable part of a comprehensive water management program.

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What is a Point-of-Use filter?

A Point-of-Use filter is a unit that attaches to a water tap, showerhead or faucet, or is used in-line such as on an ice machine.  Filters protect against microorganisms like mold, yeast, and bacteria, e.g., Legionella pneumophila and Pseudomonas aeruginosa.

How does a POU filter work?

Inside a typical unit there is a membrane with very small pores.  This membrane filters out particulates in the water that are above a certain size, including microorganisms.  For example, one model filters out everything above 0.1 μm, leaving only “sterilizing grade” water coming out of the tap.  The filters are designed to minimize the potential for clogging, and are easy to install and remove.

Why would I use a POU filter?

Having a POU filter provides peace of mind.  If Legionella, or another problem microorganism, were to be detected in your potable water system, immediately installing POU filters can be a safe and effective response and allow time to carefully evaluate other corrective actions as necessary.  Filters can be used continuously in high risk areas, such as areas in healthcare facilities with immunocompromised patients, as well as for rinsing other medical devices.  It is important to use the filter that best suits your facility’s requirements – ask your water treatment provider or infection control professional for advice.
Point of Use Filter

How long do the filters last before they have to be changed?

The units need to be replaced periodically, since they fill up with the material being filtered out of the water.  Models do come with various lifespans.  For example, some manufacturers offer a product designed to be used for 31 or 62 days.  The lifespan that is right for you will depend on the application.

Is any maintenance required?

POU filters are low maintenance; however, staff should be educated with respect to why filters are in place and the importance of not removing or replacing them until the appropriate time.  It is a good idea to do periodic checks to ensure filters are working properly, including checking for appropriate pressure and flow rates.


Ensuring a safe water supply should be a priority for all building designers, owners, and operators, and POU filters can be part of the solution.  You should consider that they are only one tool in the toolbox, and can be a significant expense depending on the number used and length of time in place.  Industry best practices require certain facilities to assess risk and develop a water management program (also called a Water Safety Plan).  This is a comprehensive approach considering many control measures, with the result being a tailored plan for managing risk from Legionella.


Stephen Betts is a Water Safety Group Representative with broad experience in environmental management and compliance programs. He has degrees in Chemistry from Queen’s University and Planning from Dalhousie University. He works with our clients to develop and implement successful water safety programs that aim to mitigate risks associated with pathogens and other contaminants in building water systems. In his spare time, Stephen enjoys listening to and playing music.

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