Studies Funded by WQRF

Recent Studies

Contaminant Occurrence Study and Map (2020)

The Contaminant Occurrence Study and Map includes data in the United States for regulated drinking water contaminants that have an enforceable level (MCL or Action Level) above the health-based goal level (MCLG) and also aesthetic contaminants that can cause taste, odor and color or staining issues. ​The Contaminant Occurrence Study collected water quality data over the last 10 years for 57 different drinking water analytes in the United States. An online, interactive mapping tool is available on and provides a visual illustration of this occurrence data. 

Click here for a copy of the Contaminant Level Occurrence Above the MCLG executive summary, and members can log in for a copy of the full report.

Click here for a copy of the Aesthetics Level Occurrence Study executive summary, and members can log in for a copy of the full report.

The first report from Phase 2 includes occurrence analyses for the following analytes: alkalinity, chloride, corrosivity, langelier index, nitrate, nitrate-nitrite, nitrite, orthophosphate, total phosphate and sulfate. Members can log in for a copy of the full report.

The Phase 2B report includes statistical summaries for 99 analytes including the following analytes: 1,4-dioxane, copper, hexavalent chromium, PCE, Uranium, Radium, Calcium, Magnesium, Radon and Strontium. Members can log in for a copy of the full report.

Final Barrier Cost-Benefit Study (2017)

This study establishes a cost-benefit relationship of using a point-of-use (POU) device as a Final Barrier in homes to significantly lower health risks by removing/reducing contaminants of concern from drinking water to the lowest feasible level.

Your member login is required to access the full report.

Boil Water Notices in the U.S., 2012-2014

This study is the first comprehensive database of the cause for boil water notices (BWN) issued in the 155,000 documented public water systems in the United States. The study concludes most BWN’s (53%; n=11,131) were issued as a precaution for the possibility of microbial contaminants due to leaks or breaks in a water main.The report concludes that due to the randomization of these events, an appropriate risk management method that could be utilized is point-of-use or point-of-entry water treatment certified for microbiological reduction. Steps for proper sanitization of treatment equipment after a BWN event is available for members in the WQA Knowledge Base

Click here for a copy of the Executive Summary. Members may download the electronic toolkit of the study here and access the full report here

Reduction of Effluent Chloride Study 

The final report of this study is available on Madison Metropolitan Sewerage District's (MMSD) website. The study can be used as a model approach in areas struggling with chloride discharge. The final conclusions were that on average, softener optimizations could reduce the concentration of chlorides by 27% while replacement with systems meeting 4,000 grains/lb. salt efficiency could reduce the concentration of chlorides by 47%

WQA members can find articles regarding softener optimization for efficiency in the WQA Knowledge Base and download the electronic toolkit here.  

Environmental Impact Study

This study was undertaken to investigate the effect home ion-exchange water softeners may have on the performance of onsite septic tanks. The data indicate that the use of efficiently operated water softeners (at or above ~3000 gr/lb salt efficiency) improves septic tank performance, while the use of very inefficient home softeners (at or below ~1000 gr/lb salt efficiency) may have a negative effect on solids discharge to the drain field.

  • Click here to download the executive summary as a PDF.
  • Click here to download the full report as a PDF (WQA members only).


Softened Water Benefits Study (Energy and Detergent Savings)
This independent study tested devices fed with softened and unsoftened water under controlled laboratory conditions designed to accelerate the waterside scaling in the device and quantify the performance efficiency. For clothes washing, the study investigated stain removal with varying levels of water hardness, detergent dose, and temperature. For dish washing, the study included tests for removing difficult soils and spot and film evaluation with varying levels of water hardness and detergent dose. 

  • Click here to download the executive summary as a PDF.
  • Click here to download the full report as a PDF (WQA members only).

Past Studies

Home Water Corrosion Study 
Initiated as a response to uninformed opinions among various groups that softened water was more corrosive than the source water. These beliefs developed due to confusions between naturally soft or low total dissolved solids (TDS) content water, which is aggressive, and softened hard water, which is no more aggressive than its source water. The study’s findings supported the industry’s position that softened water poses no corrosion problems.

Chloroform Study 
Laid the ground work in NSF/ANSI standards for carbon filter manufacturers to test effectiveness for chloroform and claim effectiveness for 53 regulated synthetic organic chemicals.

Leaching of Metals from Household Plumbing Materials: Study of the Impact of Home Water Softeners
The results demonstrated that there is no link between softened water and corrosion. This U.S. Environmental Protection Agency study, funded by WQRF, provides scientific support that ion exchange water softening does not affect the corrosivity of water.

Characterization of Heterotrophic Bacterial Populations in Point-of-Use Water Treatment Systems 
WQRF cooperatively sponsored the NSF/World Health Organization (WHO) International Symposium on Heterotrophic Plate Count (HPC) Bacteria in Drinking Water Public Health Implications, convened in Geneva, Switzerland in April 2002. The WHO Expert Committee’s resulting conclusions are that "increases of HPC (microorganisms) (due to growth) in these (domestic water devices, including water softeners, carbon filters, etc.) therefore, do not indicate the existence of a health risk." WQRF research continues to show that if the average consumer in the United States uses a point-of-use (POU) water treatment device at home on a weekly basis, they will ingest less than 2 percent of their total bacterial intake from the POU-treated water. The literature review also demonstrated that the same types of HPC bacteria are common in foods. Thus, extensive scientific evidence has objectively and consistently verified that HPC bacteria in POU- and POE-treated drinking water are not harmful.

WQRC Septic Tank/Water Softener Studies
This 1978 research report combines the scientific data for two separate studies funded by the Water Quality Research Council. Part I of the report is a summary of the research concepts and results. Part II is devoted to the “Potential Effects of Water Softener Use on Septic Tank Soil Absorption On-Site Waste Water Systems” study, completed by the University of Wisconsin – Madison. Part III of the report is focused on The National Sanitation Foundation’s study, “The Effect of Home Water Softener Waste Regeneration Brines on Individual Aerobic Wastewater Treatment Plants.” Overall, the studies concluded that it is better to discharge water softener wastes to septic tank systems than to separate dry wells or ditches.

  • Click here to download the full report as a PDF (WQA members only).