Certification Standards for Water Treatment Systems

Mar 27th 2017

Our Drinking Water Treatment Systems and components have been third party tested and certified to meet established National Sanitation Foundation (NSF) and/or American National Standards Institute (ANSI) Standards and/or State Certification requirements. Certification means that a credible, objective independent third party has tested and verified that the certified product complies with specific NSF/ANSI standards. Generally, when a Drinking Water Treatment System is certified to these standards, there are 5 basic requirements:

  1. Contaminant reduction claims are true.
  2. The system does not add anything harmful to the water.
  3. The system is structurally sound.
  4. The advertising, literature and labeling are not misleading.
  5. The materials and manufacturing process used do not change.

There are several certification programs that manufacturers of Drinking Water Treatment Units use to certify their products to industry standards such as the National Sanitation Foundation (NSF), Underwriter's Laboratories (UL) and Water Quality Association's Gold Seal Program. Additionally, several states such as California and Iowa have programs in which Drinking Water Treatment Systems and/or related plumbing materials need to registered or certified if they are to be sold within that state.

To learn more about the specific certification programs and standards, visit the corresponding organizations:

NSF International

Water Quality Association (WQA) Gold Seal Program

Underwriters Laboratory (UL)

State of California Certified Residential Water Treatment Devices

I owa Water Treatment System Registration Program

ANSI/NSF Standards for Drinking Water Treatment Units

These standards represent the most common standards established by NSF for domestic drinking water systems and shower filters.

NSF/ANSI Standard 42: Aesthetic Effects

Units are evaluated for material safety, structural integrity and accurate product literature. This standard primarily deals with Particulate and Chlorine removal, appearance and Taste and Odor claims.


A chlorine reduction claim means the system reduces the concentration of chlorine in the water. This category is broken down into classes that represent a certain level of Chlorine removal.

  • Class I - 75% or greater Chlorine reduction
  • Class II - 50% - 74% Chlorine reduction
  • Class III - 25% - 49% Chlorine reduction


A performance claim for Particulate removal means the system removes particles of a certain size based on the following classes:

Class I - Reduces 85% of particles 0.5 to < 1 microns in size

Class II - Reduces 85% of particles 1 to < 5 microns in size

Class III - Reduces 85% of particles 5 to < 15 microns in size

Class IV - Reduces 85% of particles 15 to < 30 microns in size

Class V - Reduces 85% of particles 30 to < 50 microns in size

Class VI - Reduces 85% of particles equal to or greater than 50 microns in size

NSF/ANSI Standard 53: Health Effects

Units are evaluated for material safety, structural integrity and accurate product literature. This standard is concerned with contaminants that may pose a health risk such as:


Volatile Organic Compounds (V.O.C.'s)

Inorganic Chemicals (nitrate, mercury, asbestos, lead, fluoride, etc.)




Pesticides and Herbicides

Trihalomethanes (THM's)


Volatile Organic Chemicals (V.O.C.'s)

A performance claim for V.O.C. reduction means the system reduces the concentration of all of the following 50 contaminants. Some of these chemicals can be tested individually for performance claims.

Disinfection By-Products Chemicals
chloropicrin benzene
haloacetonitriles (HAN) carbon tetrachloride
bromochloroacetonitrile chlorobenzene
dibromoacetonitrile 1,2-dichloroethane
dichloroacetonitrile 1,1-dichloroethylene
trichloroacetonitrile cis-1,2-dichloroethylene
haloketones (HK) 1,2-dichloropropane
1,1-dichloro-2-propanone cis-1,3-dichloropropylene
1,1,1-trichloro-2-propanone ethylbenzene
trihalomethanes hexachlorobutadiene
chloroform hexachlorocyclopentadiene
bromoform styrene
bromodichloromethane 1,1,2,2-tetrachloroethane
dibromchloromethane tetrachloroethylene
tribromoacetic acid toluene
Pesticides trans-1,2-dichloroethylene
carbofuran 1,2,4-trichlorobenzene
dibromochloroproane (DBCP) 1,1,1-trichloroethane
o-dichlorobenzene 1,1,2-trichloroethane
p-dichlorobenzene trichloroethylene
endrin xylenes
ethylene dibromide (EDB) Herbicides
heptachlor (H-34, Heptox) alachlor
heptachlor epoxide atrazine
methoxychlor dinoseb



2,4,5-TP (silvex)


A performance claim for cysts indicates the system reduces the concentration of parasitic cysts by at least 99.95%. The cysts included in this claim are Cryptosporidium, Giardia, Toxoplasma and Entamoeba.


A claim for turbidity reduction means the system removes fine particulate matter that makes water appear cloudy to a level below the U.S. EPA Maximum Contaminant Level.


A performance claim for lead reduction demonstrates the system's ability to reduce the concentration of lead below the U.S. EPA Maximum Contaminant Level.

NSF/ANSI Standard 58: Reverse Osmosis Systems

This standard is concerned with the performance of Reverse Osmosis drinking water systems and checks for material safety, structural integrity and accurate product literature. The performance claims include the following contaminants:

Arsenic Reduction

Asbestos Reduction

Barium Reduction

Cadmium Reduction

Copper Reduction

Cyst Reduction

Fluoride Reduction

Hexavalent Chromium Reduction



Lead Reduction

Mercury Reduction

Nitrate/Nitrite Reduction

Radium 226/228 Reduction

Selenium Reduction

TDS Reduction

Trivalent Chromium Reduction

Turbidity Reduction

VOC Reduction

NSF/ANSI Standard 177: Shower Filter Systems

This standard is specific to residential shower filter systems. Along with material safety, structural integrity and accurate product literature, units must meet free available chlorine reduction standards. Systems must reduce an influent challenge of 2.0 mg/L free available chlorine by at least 50% throughout their rated service life when tested at the manufacturer’s recommended service flow rate (at least 1.0 gpm).