Risks to Water Quality - UV Systems

Posted by Jeff Wahl on 6/9/2016
Risks to Water Quality - UV Systems
“Too often home owners trust the water implicitly when a Residential UV System is installed.”

When you purchased a UV System it was to protect the water in your home, cottage or business from bacteria present in water. It is likely that no one informed you of the risk associated with Power Outages or Proper Maintenance and the assumption is made that if the power light is on, the system is working properly and treating the water. This is not always the case.

Wahl H2O - Educating Through AwarnessWater Cross Contamination in Hydro Outages
Quite often people will turn on taps or flush toilets during an outage and inadvertently cross contaminate their plumbing without ever knowing it. Bacteria passes through the UV when it is not on and when power is restored the assumption is that everything is okay with the water because the UV is operational again.

This may not be the case as bacteria have the opportunity to replicate on the other side of the operating UV Light. Simply turning the UV System back on does not guarantee the water is bacterial free as there is no residual disinfecting occurring in the pipes. Once cross contamination  has occurred, a proper pipe disinfection including the hot water tank should be performed.

The Importance of Proper Water Treatment for UV Sleeves
Proper Maintenance of the UV System
Water Quality can have an impact on the UV’s ability to “see” through the Quartz Sleeve. For simplicity this can be illustrated using a common light bulb analogy. If you paint a light bulb orange and turn it on, there is power and the light is on but it will not shine very brightly. The same analogy applies for a Quartz Sleeve, if Iron (orange staining) exists in the water there can be a “coating” of the Quartz Sleeve and diminish the strength of the UV Ray. This principal also applies for Water Hardness (white scaling) and Sulphur (rotten egg smell, black staining).

Turbid water (sediment) will also interfere with the UV Ray as microorganisms can “hide” in the particles and not be inactivated inside the chamber. If the water is not clear and has a colour, it is possible that a low UV Transmittance (Water Clarity) exists and the UV Ray will not shine properly. Proper Maintenance and Pre-Treatment of the water is a Requirement for Proper Water Disinfection.

For more information visit Water Cross Contamination - What is the Risk?

Replace UV Lamps at 12 Month Intervals
Many systems are equipped with an automatic lamp replacement counter or reminder to ensure that the lamp is replaced at the required 1 Year Interval. There are systems which do not have this feature and rely on the customer to know that the lamp must be changed. Most residential UV Systems require a lamp change after 12 months of running time as the lamps loose their intensity. The power indicator on most units is not a lamp replacement indicator and many homeowners are unaware of this. They do not change their lamp for years or until it burns out which has the potential to result in poor water quality while the homeowner is completely unaware.

Where to Locate a Solenoid Valve on a UV SystemInstall an Automatic Solenoid Shut Off Valve
A solenoid valve is a device installed in plumbing that opens and closes to turn a water supply on or off. The operation of the valve is fully automatic and there are no actions required by the consumer to start or stop the valve. It is important to correctly match piping sizes and the connection type to your plumbing when selecting a solenoid valve. The valve is available for use with all UV Systems and plugs directly into a standard electrical receptacle.

It should be installed prior to the inlet of the UV System and will close immediately when there is no power preventing water from entering into the UV chamber. It reopens when power has been restored and is effective at preventing water cross contamination during power outages.

Investing in a Solenoid Valve provides a second layer of protection for your Ultra Violet Disinfection System and prevents unnecessary plumbing disinfection.



If you own a UV Light consider all of the necessary requirements to keep the water safe and if you are unsure contact a Certified Water Treatment Professional who can assist you to ensure that your water is safe.


Volume 1 – Issue 4 Wahl H2O - Water Awareness
Copyright 2016 Jeff Wahl – Wahl Water | All Rights Reserved
Contact Jeff via email jeff@wahlwater.com

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