Residential Water Softeners Release Carbon, Consume Chlorine, and Require Remediation after Hydrocarbon Contamination

Water quality impacts of new ion exchange point-of-entryresidentialsofteners and their ability to be decontaminated following hydrocarbonexposure were investigated. During startup, significant amounts oftotal sulfur (445 +/- 815 mg/L) and total organic carbon (937 +/- 119 mg/L) were released into the drinking water that flowed throughthe softeners. Particulate organic carbon was released until the thirdregeneration cycle, and resin may also have been released. After oneweek of device use, softeners continued to cause organic carbon levelsto be four to five times greater than background levels. Leached materialsfrom the ion-exchange resin contributed to chlorine decay. When resinswere exposed to hydrocarbon-contaminated water, they sorbed benzene,toluene, ethylbenzene, and xylenes (BTEX) and then desorbed the contaminantsinto drinking water during a 15 day flushing decontamination period.On day 15, benzene exceeded the federal drinking water limit for twoof the four resins. The aged resin contributed to the greatest chlorinedecay rates and sorbed and then retained the least amount of BTEX.Scale and biofilm on the aged resin likely prompted disinfectant reactivityand inhibited BTEX diffusion into the resin. Study results show thatsofteners exposed to hydrocarbon-contaminated water may need to berepeatedly flushed to remove BTEX contamination or be replaced. Additionalwork is recommended to better understand softener impacts on drinkingwater quality. Residential softeners remove hardnessfrom water, but littleis known about their impacts on other building water chemical andmicrobiological characteristics. This study describes their impactsand ability to be cleaned after hydrocarbon contamination.

Automated summary

The impact of new ion exchange point-of-entry residential softeners on water quality, as well as their ability to be decontaminated after hydrocarbon exposure, was studied. The release of total sulfur and total organic carbon into the drinking water during startup was significant. Softeners continued to cause high organic carbon levels even after one week of use. Leached materials from the resin contributed to chlorine decay and sorbed and desorbed contaminants. The study suggests that softeners exposed to hydrocarbon-contaminated water may require flushing or replacement.