NSF Standards
Product Testing & Certification
NSF International, also known as the National Sanitation Foundation, has become well known as an independent third-party certifier for the drinking water industry.
NSF International has established consensus standards and testing protocols for drinking water treatment devices used by all other testing laboratories. Once a system has become “NSF Certified”, then the consumer can feel confident that the system will perform up to the manufacturer’s claim. For comparison purposes, I’ve listed each NSF International standard, which has been adopted by many states, for drinking water treatment systems.
NSF Standard 42
NSF Standard 42 deals with any claims of taste, odor, color, and other aesthetic effects, which includes the reduction of chlorine and particulate matter. The classes are as follows;
1. Taste, Odor and Chlorine Reduction
Many water municipalities use chlorine for water disinfection. Unfortunately, this often produces an undesirable taste or odor, as well as Trihalomethanes, a know carcinogen. Certified drinking water treatment devices have been grouped into the following categories based on the efficient reduction of chlorine throughout the life of the system.
CLASS I – Reduces chlorine by 75-100%
CLASS II – Reduces chlorine by 50-74%
CLASS III – Reduces chlorine by 25-49%
2. Particulate Reduction
Water that appears cloudy or turbid is caused by particulate matter found in the water. Drinking water systems that have been Certified for particulate reduction have been shown, through testing, that they will reduce specific sized particles. Drinking water systems are Certified as meeting one of the following categories;
CLASS I – 0.5-1 micrometers (sub-micron)
CLASS II – 1-5 micrometers (extra-fine)
CLASS III – 5-15 micrometers (medium-fine)
CLASS IV – 15-30 micrometers (fine)
CLASS V – 30-50 micrometers (medium coarse)
CLASS VI – 50 micrometers or large (coarse)
NSF Standard 53
Contaminants that are considered potential health hazards, such as microbiological, chemical, or particulate (cysts) in nature, fall under NSF Standard 53. Any water system that attempts to reduce or remove specific contaminants from a public or private drinking water source will be Certified under this standard. It should be noted that, while a system may be effective in reducing or removing one or more contaminant, in this standard, it is not required that they control all contaminants. The contaminants included under this standard are as follows;
1. Chemical and Heavy Metals
Includes chemical and heavy metal contaminants, such as lead, lindane, 2, 4, -D, asbestos, trichloroethane and others.
2. Volatile Organic Chemicals (VOCs)
VOCs are chemicals that are emitted as gases from certain solids or liquids. They are delivered from a variety of paint thinners, cleaning supplies, pesticides, office equipment, correction fluid, craft materials, such as glue, and permanent markers.
3. Turbidity
A cloudiness or haziness to water, or other fluid, caused by suspended solids that can’t generally be seen by the naked eye. The effectiveness of water disinfection can be decreased by increased turbidity, simply because bacteria can become attached to the suspended solid.
4. Cysts
Cysts are pockets that contain single cell parasites, which are very resistant to chlorine. Cysts can cause disease, often accompanied with symptoms, such as abdominal cramping diarrhea. The most common cysts are Giardia and Cryptosporidium, both of which originate from sewage or animal waste.
5. Total Trihalomethanes (TTHMs)
TTHMs are a byproduct of chlorinated water that contains natural organics. Decomposition of leaves, wood, grass, and mineral waste can result in the formation of humic compounds. TTHMs form when organic compounds combine with chlorine and have been known to cause cancer.
6. Organic Compounds
Organic compound chemicals can often enter drinking water as a result of misapplied agriculture chemicals, spills or industrial discharge.
NSF Standard 55
The NSF Standard 55 covers Ultraviolet Drinking Water Systems. The specific contaminants tested are:
CLASS A – Disinfection
Designed to disinfect water that is microbiologically contaminated, but meets all other public health standards. Not intended to treat water that has a confirmed contamination source. This type of system is unable to turn wastewater into safe drinking water. This type of system should be installed on water that is visually clear.
CLASS B – Disinfection
This system contains ultraviolet lights that will need to be replaced periodically, in accordance with the manufacturer’s instructions. The ultraviolet lamps provide a supplemental bactericidal treatment for both, treated and disinfected, drinking water that has been deemed safe for human consumption by the local jurisdiction. The system is designed to reduce normally occurring non-pathogenic microorganisms only.
NSF Standard 58
The NSF Standard 58 covers Reverse Osmosis Drinking Water Systems.
NSF Standard 62
The NSF Standard 62 covers Distillation Drinking Water Systems. The specific contaminants covered under this standard are:
1. Arsenic
2. Barium
3. Cadmium
4. Copper
5. Fluoride
6. Hexavalent Chromium
7. Lead
8. Mercury
9. Microbiological Performance
10. Nitrate/Nitrite
11. Selenium
12. TDS (Total Dissolved Solids)
13. Trivalent Chromium
