Frequently Asked Questions


Water Quality FAQs

WQA Professional Certification FAQs

WQA Certified Products FAQs

Who is the Water Quality Association?

The Water Quality Association (WQA) is a not-for-profit international trade association representing the residential, commercial and industrial water treatment industry. WQA maintains a close dialogue with other organizations representing different aspects of the water industry in order to best serve consumers, government officials, and industry members.WQA is a resource and information source, a voice for the industry, an educator for professionals, a laboratory for product testing, and a communicator to the public.

What is water quality improvement?

Water treatment, or conditioning, is the processing of water, by any means, to modify, enhance, or improve its quality or to meet a specific water quality need, desire, or set of standards. Water treatment involves disinfecting and purifying untreated ground and surface water. Water quality is important for health, and it is good for appliances, too!

How can I tell if the water in my home is safe to drink?
There are 3 simple steps to making sure the water in your home is safe and healthy to drink:

  1. Consult: Click here to find a water professional in your area to consult with.
  2. Test: Click here to find a listing of EPA accredited labs in your state. The results from a water analysis will help determine the best treatment technology.
  3. Treat: Click here to find a certified product.

How do I read a water analysis report?
Begin by comparing your water analysis results against the EPA’s regulated Maximum Contaminant Levels (MCLs). You will notice there are regulated levels (MCLs) for health effects, and there are non-enforceable, unregulated goal levels for aesthetics effects (taste, odor, staining, etc.).  Also note, the unit of measure ug/L is equal to ppb/L (parts per billion), and the unit of measure mg/L is equal to ppm/L (parts per million).

  • National Primary Drinking Water Regulations (NPDWRs or primary standards) are legally enforceable standards that apply to public water systems.
  • Maximum Contaminant Level (MCL) is the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards.
  • National Secondary Drinking Water Regulations (NSDWRs or secondary standards) are non-enforceable guidelines regulating contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water.
  • Maximum Contaminant Level Goal (MCLG) is the level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-enforceable public health goals. 

Is softened water corrosive?
No. The suggestion that ion exchange water softeners promote corrosion is a misperception and the suggestion to use scale build up as a corrosion control method is inappropriate as proven by the EPA.  The conclusions were drawn from an EPA pilot study conducted by Thomas J. Sorg and Michael R. Schock of the EPA's Drinking Water Research Division as project manager and principal investigator. Simply put, the removal of hardness with an ion exchange water softener does not affect the factors which cause or even accelerate corrosion.  Corrosion is caused by a change in the pH or carbon dioxide concentration, the dissolved oxygen concentration, or the total chemical concentration of minerals. None of these factors is affected by water softeners.

What is hard water?
Hard water is a common quality of water which contains dissolved compounds of calcium and magnesium and, sometimes, other divalent and trivalent metallic elements. The term hardness was originally applied to waters that were hard to wash in, referring to the soap wasting properties of hard water. Hardness prevents soap from lathering by causing the development of an insoluble curdy precipitate in the water; hardness typically causes the buildup of hardness scale (such as seen in cooking pans). Dissolved calcium and magnesium salts are primarily responsible for most scaling in pipes and water heaters and cause numerous problems in laundry, kitchen, and bath. Hardness is usually expressed in grains per gallon (or ppm) as calcium carbonate equivalent.

The degree of hardness standard as established by the American Society of Agricultural Engineers (S-339) and the Water Quality Association (WQA) is as follows:



What causes hard water?
Hardness minerals – calcium and magnesium – are in plentiful supply. While they are not found in their elemental form in the earth, they occur in combination with other elements in an abundance of forms. Common calcium minerals include chalk, limestone, and marble. These substances are chiefly calcium carbonate (CaCO3) or mixtures of calcium and magnesium carbonates and other impurities. The hardness in water that is caused by calcium, magnesium, and other cations is usually described in terms of the calcium carbonate equivalent.

How is hard water treated?
Softening hard water can mitigate many of its objectionable effects. Water softening can be done either at point of entry or point of use. One of the unique advantages offered by point-of-use water softening is the opportunity for homemakers to have either hard or soft water for drinking. This choice is not available if the water supply is softened municipally. Hardness minerals can be reduced in water to make it “softer” by using one of three basic means:

  • Chemical softening—lime softening, hot and cold; lime-soda softening   
  • Membrane separation softening—Nano filtration 
  • Cation exchange softening—inorganic, carbonaceous, or organic base exchangers

Softening water for home needs is done almost exclusively through the use of cation exchange.

Is softened water safe for plants?
Where the amount of hardness minerals in the water is only moderate (less than 10 gpg), it is doubtful whether the sodium concentration would be sufficient to be a serious hazard to plants. Most house plants require specific soil conditions for healthy growth. Many thrive best in slightly acid soils. If there is a high hardness concentration in the water being softened, the necessarily higher sodium concentration of the softened water may be harmful to plants.

For outside sprinkling purposes, the use of softened water, for economy reasons, is not recommended unless necessary to prevent iron stains on buildings and concrete. Again, where the concentration of hardness minerals is heavy, the sodium salts replacing them might retard growth and might be sufficient to kill the grass.

What is reverse osmosis?  
Sometimes shortened to the acronym RO, these systems force water, under pressure, into a module that contains a semipermeable membrane and a number of other filtration steps. A typical RO system has a prefilter designed to capture larger particles, chlorine, and other substances; a semipermeable membrane that captures more contaminants; an activated carbon filter that removes residual taste, odor, and some organic contaminants; and a storage tank to hold the treated water for use. 

How does reverse osmosis work? 
This process is called "reverse" osmosis because the pressure forces the water to flow in the reverse direction (from the concentrated solution to the dilute solution) to the flow direction (from the dilute to the concentrated) in the process of natural osmosis. RO removes ionized salts, colloids, and organic molecules down to a molecular weight of 100.

You can get a whole-house RO, but more commonly, a point-of-use RO system would be on your countertop or installed under the sink. They’re great for treating water for cooking and drinking, but they don’t usually produce large amounts of treated water — more like 3 to 10 gallons a day. For that reason, typically people choose to install RO-treated faucets in the most popular areas of the home such as kitchens and bathrooms, as opposed to installing it for every drinking tap. Just like any other kind of filter technology, reverse osmosis systems require regular maintenance. That includes periodically replacing the unit’s prefilters, postfilters, and membrane modules.

Is RO water safe to drink?
Consumption of low-TDS water, such as that which results from RO treatment, does not pose any health concerns for healthy populations. Essentially, in normal, healthy individuals, the body is able to maintain homeostasis, which is what controls the release and adsorption of minerals, regardless of the TDS levels in the ingested fluids.

In cases of malnourishment, water can be a good source of nutrients. For people with an adequate amount of food, however, the level of nutrients obtained through water is negligible compared to food.

The pH of RO water is more acidic than tap water containing dissolved minerals, but not by much, and certainly not as low as that of orange juice, lemon juice, or our stomach acid. Upon contact with our saliva, the effects of the pH of RO water are quickly negated. 

What causes etching on glassware?
Very high water temperatures in automatic dishwashers can cause detergent phosphate compounds to change into aggressive forms. If enough dish soil or water hardness is available, it will react with the most aggressive of these sequestering phosphates. Otherwise excessive detergent agents can actually extract elements directly from the glassware composition.

In early stages, etching appears as rainbow-colored film similar to an oil-on-water film. As etching progresses, this film changes to opaqueness, which appears similar to filming except that it cannot be removed or repaired since etching is an eating away of the glass.

What is WQA's Professional Certification Program?
The WQA Professional Certification Program helps consumers and employers identify individuals in the point-of-use/point-of-entry water quality improvement industry who have demonstrated a certified level of professional expertise and are dedicated to high professional standards. WQA certification is a voluntary credentialing process. To achieve any WQA-certified title, the candidate must pass a comprehensive exam and accept the WQA Code of Ethics for the Water Quality Improvement Industry.

What is a certified product?
WQA's Gold Seal Product Certification Program is accredited by the American National Standards Institute (ANSI) and the Standards Council of Canada (SCC) to test and certify products and chemicals to industry standards. Products that display the Gold Seal provide assurance that they have been rigorously tested and meet the requirements of the standard, WQA's program polices, and WQA's plant inspection policies for which WQA maintains certification. WQA Gold Seal product certification includes:​​​

  1. Material Safety: Wetted materials are tested to ensure they are safe for contact with drinking water
  2. Structural Integrity: Systems and components subject to pressure are tested to ensure they do not leak or fail under normal operating conditions (if necessary for the type of system)
  3. Performance Testing: Systems are tested to certify the reduction claims made on product packaging
  4. Product Literature and Packaging: Reviewed to ensure product literature and packaging meet the standard requirements and do not make false or misleading claims
  5. Facility Assessment: Each manufacturing facility must be audited to ensure a quality system
Who is the American National Standards Institute (ANSI) and what do they do?

ANSI promotes and facilitates voluntary consensus standards and conformity assessment systems, and safeguards their integrity. ANSI coordinates the U.S. voluntary consensus standards system, providing a neutral forum for the development of policies on standards issues and serves as a watchdog for standards development and conformity assessment programs and processes. Additional information regarding ANSI can be found at:

Who develops the standards for water treatment equipment?
ANSI facilitates the development of American National Standards (ANS) by accrediting the procedures of standards developing organizations (SDOs). These groups work cooperatively to develop voluntary national consensus standards. Accreditation by ANSI signifies that the procedures used by the standards body in connection with the development of American National Standards meet the Institute’s essential requirements for openness, balance, consensus and due process. Due process is the key to ensuring that ANSs are developed in an environment that is equitable, accessible and responsive to the requirements of various stakeholders. The open and fair ANS process ensures that all interested and affected parties have an opportunity to participate in a standard's development. It also serves and protects the public interest since standards developers accredited by ANSI must meet the Institute's essential requirements and other due process safeguards. The most notable SDO for the drinking water treatment industry is NSF International.

How do certification bodies achieve ANSI accreditation?
The program is overseen by the ANSI Product Certification Accreditation Committee (ACC), established by the ANSI Board of Directors. The responsibilities of the committee include approving the key policy documents, reviewing the process of evaluation, accreditation decisions, and monitoring/auditing programs. Certification bodies must show third party status, participate in assessments, and prove compliance to all aspects of ISO/IEC Guide 65 as well as other ANSI standards.

What is the difference between WQA and NSF International?

Water Quality Association  NSF International
Operate a Testing and Certification Program for Water Treatment Products, Chemicals, and Plumbing Components to NSF/ANSI Standards Operate a Testing and Certification Program for Water Treatment Products, Chemicals, Plumbing Components to NSF/ANSI Standards, as well as other areas
Testing Agency
Product Certification Agency
Testing Agency
Product Certification Agency
Standards Writing Agency
WQA's Gold Seal Product Certification Program is an accredited certification agency through the American National Standards Institute (ANSI) and the Standards Council of Canada (SCC) NSF International's Product Certification Program is an accredited certification agency through the American National Standards Institute (ANSI) and the Standards Council of Canada (SCC)
Participate and vote in the NSF/ANSI standards development/revision process Participates and vote in the NSF/ANSI standards development/revision process
Publish revised standards
Accepted by the Association of State Drinking Water Administrators (ASDWA) as an approved certification agency Accepted by the Association of State Drinking Water Administrators (ASDWA) as an approved certification agency
Maintains a public website,, with listings of all WQA-certified companies and products Maintains a public website,, with listings of all NSF-certified companies and products

What is the difference between the WQA membership logo and WQA Gold Seal?
The Water Quality Association functions with a few separate purposes including, but not limited to, being a trade organization for the water treatment industry, educating and certifying professionals, as well as, product testing and certification. Membership to the trade organization does not mean WQA has performed any testing or certification of professionals or products, these functions are separate. Membership to the trade organization requires a dues payment, provides professional education, access to studies and resources, regulatory and technical support, etc. Members allowed to use the blue WQA Member logo on their website or business card are listed in our member directory. To avoid confusion with membership versus product certification the WQA Member logo is not allowed on products or point of sale packaging.

The WQA Gold Seal Product Certification logo on a product or website would indicate WQA has evaluated and certified the product.  WQA also maintains an online registry of currently certified products and components to clear up any confusion whether a product is allowed to bear the Gold Seal. Separate logos for certified professionals and our sustainability program may also be used by those certified under the respective programs.  Please note that the Gold Seal Program, Sustainability Program and Professional Certification Program are voluntary and do not require membership in the WQA trade association.