NSF Certified vs. Non-Certified UV Systems: How to Choose

Selecting a UV system can be a difficult choice. There are many brands on the market and within each of these brands there are multiple product families from which to choose. Perhaps the most puzzling of UV system choice is the decision between purchasing an NSF or non-NSF certified UV system. This article explores NSF certification and will help you to decide if a certified or non-certified product is the right choice for you.

What is NSF?

NSF is the National Sanitation Foundation. It is a not for profit organization headquartered in Ann Arbor Michigan. NSF protects public safety by writing safety standards and testing consumer products against these standards. Their standards cover hundreds of products ranging from dietary supplements to household appliances. Manufacturers pay to have their products tested and endorsed by NSF. This shows their prospective customers that their products are safe to use and often gives them an advantage in the marketplace.

What NSF Standards Exist for UV Systems?

There are two NSF standards that apply to UV water treatment systems. NSF Standard 55 Class A, and the little known NSF Standard 55 Class B. When water professionals or regulators make reference a "certified" piece of UV equipment they are almost always talking about the NSF Standard 55 Class A. NSF Standard 55 Class A NSF Standard 55 Class A is a designation given to UV systems that are able to pass a test as outlined in the standards documentation. In order to gain NSF Standard 55 Class A designation a UV system must be able to deliver a 40mJ (millijoule) UV dose. UV dose is simply the amount of UV radiation absorbed by an organism as it passes through the UV chamber. UV dose is affected by the lamp intensity and by the flow rate. The longer an organism spends in front of a UV lamp, the higher the dose. A 40mJ UV dose was selected by NSF under recommendation by the U.S. Environmental Protection Agency. A 40mJ dose is sufficient to give 99.99% destruction of the organisms that are common drinking water contaminants. Because UV dose is tied so closely to flow rate, all NSF Standard 55 Class A systems must have a built in flow restrictor. The last criteria for passing the NSF Standard 55 Class A test is that the system must have built-in monitoring that ensures the 40mJ UV dose is always being delivered. If it is not, the system must be capable of alerting the operator. This is accomplished by equipping a UV system with a sensor. The sensor measures the amount of UV intensity being generated by the system. If it detects that insufficient light intensity is being produced, it sounds an alarm. Systems that pass the stringent NSF Standard 55 Class A testing are suitable as a primary means of disinfecting drinking wate

NSF Standard 55 Class B is a standard that pre-dates the 55 Class A designation and is rarely used or discussed any longer. Systems that are certified to 55 Class B are suitable as a secondary means of disinfecting water. This means that they must be used with another disinfection technology that is approved for primary disinfection. In other words, 55 Class B systems are used as insurance, not as the primary protection technology. Virtually every UV system on the market today would meet the criteria to achieve Standard 55 Class B certification yet there are no products that carry this designation. Manufacturers are hesitant to spend the money on a certification that won't give their customers any added assurance about the performance of their product.

Who Should Use an NSF Class A Certified UV System

UV Systems that are certified to NSF Standard 55 Class A are typically used in "public" drinking water facilities. A public facility is any facility where somebody could walk off the street and consume the water. This includes such facilities as restaurants, campgrounds, churches, and offices. NSF Standard 55 Class A certified UV systems are also used for small drinking water treatment plants and community wells. In some U.S. States and Canadian Provinces the local government has mandated that even private homes must use NSF Standard 55 Class A certified products wherever UV is chosen. In most private homes across North America however, non-certified UV systems are much more common and are typically sufficient.