Haloacetic Acids (HAA5) in Drinking Water

🩨 Health Effects

Five haloacetic acids that form as byproducts of chlorination, similar to TTHMs. Long-term exposure is associated with increased cancer risk. Some studies suggest reproductive effects at high levels.

📍 Sources in Water

Formed during water chlorination when chlorine reacts with organic matter. Levels vary seasonally, are higher in summer, and are highest in systems treating surface water with high organic content.

✅ What To Do

Activated carbon filters and reverse osmosis can reduce HAA5 levels. Point-of-use filters at the kitchen tap are practical. Check your Consumer Confidence Report for annual average levels.

📜 Regulation History

The EPA first regulated HAA5 under the Stage 1 Disinfectants and Disinfection Byproducts Rule in 1998, setting the MCL at 0.060 mg/L (60 ppb) as a running annual average. The Stage 2 D/DBP Rule (2006) strengthened compliance by requiring measurement at each individual monitoring location. The WHO sets individual guidelines for each haloacetic acid rather than a combined standard.

🔬 How To Test Your Water

Certified lab tests for HAA5 cost $75-$200 due to the specialized chromatography analysis required. Home test kits are not widely available for haloacetic acids. Your utility is required to monitor and report HAA5 levels in the annual Consumer Confidence Report. Levels tend to peak in summer months.

💧 Which Filters Remove Haloacetic Acids (HAA5)?

Activated carbon filters (NSF/ANSI 53 certified) can reduce HAA5 levels, though effectiveness varies by specific acid. Reverse osmosis (NSF/ANSI 58 certified) is also effective. Carbon filters should be replaced regularly as HAA5 removal efficiency decreases as the carbon becomes saturated.

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