By Rick Andrew
According to the US Census Bureau’s 2007 information, over 15 million US households regularly depend on groundwater wells. Most well water requires some type of treatment or conditioning to make it aesthetically pleasing for users. Some well water contains contaminants at concentrations of toxicological significance and must be treated to ensure it is safe for consumers.
There are many variables for ground water wells in terms of geological factors and water characteristics that add complexity to treatment requirements. This complexity allows knowledgeable water treatment experts to provide significant value to homeowners who have private wells. These homeowners often know that they are not happy with their water, or they want some kind of treatment, but they are at a loss to understand what type of treatment or configuration of product will suit their needs best.
As a small part of the basket of knowledge required by water treatment experts to help meet the needs of consumers with well water, let’s examine certification of contaminant reduction performance claims for well water treatment. Although addressing only a fraction of the subjects that water treatment experts must understand to assist these consumers, this topic itself has many significant details that are helpful to understand.
Aesthetic versus health contaminants
Aesthetic contaminants are those which adversely affect acceptance of the water, including taste, color, odor, or appearance, but which are not health concerns. Wells can frequently be aesthetically displeasing due to such contaminants as hydrogen sulfide, particulate matter, hardness, iron, etc. These contaminants are the most frequent issues driving consumers to contact water treatment experts for assistance.
It is important to remember, however, that certain wells can also be impacted by health contaminants. One of the most common of these is arsenic, which is a naturally occurring element. US EPA has established a maximum contaminant level (MCL) of 0.010 mg/L for arsenic. Because some geographical regions of the US tend to have groundwater that exceeds this concentration, treatment of the water for drinking purposes is required. (See Figure 1 for a map of arsenic concentrations in groundwater in the US.)
There are also other health contaminants that can occur in wells. Most of them are naturally occurring minerals or trace metals that can be found in the groundwater due to local geology. There are some exceptions to this; f. or example, nitrate and nitrite can be present in shallower wells due to agricultural fertilizer runoff, animal manure, or septic infiltration. Perchlorate can occur in groundwater in certain regions due to its use in military applications including solid rocket fuel.
Standards for aesthetic and health contaminant reduction claims
The NSF/ANSI Drinking Water Treatment Unit Standards are organized according to treatment technology and scope of contaminant reduction claims. NSF/ANSI 42 addresses aesthetic claims made on mechanical filtration and media type systems, excluding cation exchange water softeners. NSF/ANSI 53 addresses health claims on the same types of systems. Both of these standards address POE as well as POU configurations.
NSF/ANSI 44 addresses POE cation exchange water softeners and and NSF/ANSI 58 addresses POU reverse osmosis systems. NSF/ANSI 62 addresses POU/POE distillation systems. See Figure 3 for a breakout of applicable product types and claims by standard. See Figure 4 for a list of applicable product types and standards by claim.
These figures provide a matrix for determining types of devices that can be certified to treat various contaminants. Water treatment experts should be aware that these technologies are capable of treating more contaminants that what is described in Figures 3 and 4. Some contaminant reduction claims that can be certified have been omitted from these Figures because those contaminants are not typically associated with groundwater wells.
There are other contaminants that can be treated by a given technology, but the standard(s) does not currently include criteria for making a contaminant reduction claim. Although the standards are continually evolving to address new contaminants and technologies, these developments take time and research to ensure that they are credible.
An example of a contaminant reduction claim that is in the process of development is perchlorate reduction under NSF/ANSI 53. This claim will apply to ion exchange systems, both POE and POU, designed for perchlorate reduction. A technical task group has been working on this claim very diligently and and they expect to have their work completed sometime in 2010, with the culmination of their work being the claim added to NSF/ANSI 53.
Groundwater wells – a great POU/POE application
The population distribution in the US and the number of homes located in suburban and rural areas lead to a large segment of the population being served by groundwater wells as opposed to public water supplies. Because this groundwater typically requires treatment to make it aesthetically pleasing and and because it sometimes carries significant concentrations of health contaminants, there is a large market for properly applied POU/POE treatment.
Given the options available in the marketplace, the issues with installation and maintenance and and the lack of knowledge of typical consumers, this creates an excellent opportunity for water treatment experts to provide these consumers with real value. Although the breadth and depth of knowledge necessary to truly serve the consumer is great, an understanding of contaminant reduction claims and certification options can provide a small portion of this knowledge base for these experts. Hopefully the figures in this article can serve as a handy vehicle to neatly package this knowledge for reference.
- US Census Bureau. Current Housing Reports, Series H150/07, American Housing Survey for the United States: 2007, U.S. Government Printing Office, Washington, D.C.: 20401, Printed in 2008. Available at http://www.census.gov/prod/2008pubs/h150-07.pdf (PDF, 6.82 mb, 642 pages).
About the author
Rick Andrew is Operations Manager of the NSF Drinking Water Treatment Units Program for certification of POU/POE systems and components. Prior to joining NSF, his previous experience was in the area of analytical and environmental chemistry consulting. Andrew holds a Bachelor’s Degree in chemistry and an MBA from the University of Michigan. He can be reached at (800) NSF-MARK or email: [email protected] .