P-dichlorobenzene 1,4-Dichlorobenzene (p-DCB)
C₆H₄Cl₂·Affects liver, kidneys
The active ingredient in mothballs and toilet bowl deodorizers. A household-source VOC that also contaminates groundwater near chemical and waste sites.
C₆H₄Cl₂
EPA limit
0.075 mg/L (MCL)
Most at risk
Households on private wells near landfills, chemical plants, or heavy mothball/deodorizer use
Found in
City water · Well water · Industrial areas
AquaOx filters
YesActivated coconut shell carbon
What it does to you
Health effects
p-Dichlorobenzene (1,4-DCB) primarily targets the liver and kidneys at chronic exposure. Animal studies document hepatic damage, kidney effects, and tumor formation, and the EPA's MCL is set to keep human exposure below the levels associated with these effects.
The International Agency for Research on Cancer classifies 1,4-DCB as Group 2B (possibly carcinogenic to humans) based on animal evidence of liver and kidney tumors. The EPA classifies it as a possible human carcinogen. The MCL of 0.075 mg/L incorporates both cancer and non-cancer endpoints.
Acute high-level exposure causes eye and respiratory irritation, headache, and central nervous system effects. Indoor air exposure from heavy mothball or deodorizer use can contribute substantially to total body burden, often exceeding drinking-water exposure.
Where it comes from
How it gets into your water
Unlike most VOCs, 1,4-DCB has a significant household source: it is the active ingredient in mothballs, toilet bowl deodorizers, and air fresheners. Disposal of these products and rinsing of mothball-treated fabrics introduces 1,4-DCB into wastewater. Sewage treatment plants reduce but do not fully remove the compound, so trace levels appear in surface water downstream of urban areas.
Industrial sources include chemical manufacturing where 1,4-DCB is used as an intermediate for dyes, pharmaceuticals, and pesticides. Landfill leachate from disposed deodorizer products and industrial waste is a documented groundwater contamination pathway.
Mothballs & deodorizers
Wastewater from household use
Chemical manufacturing
Dye and pharmaceutical production
Contaminated wells
Near landfills or industrial sites
Landfill leachate
Disposed deodorizer products
Find out for yourself
Is it in your water?
Public water utilities test for 1,4-dichlorobenzene and report results in the annual Consumer Confidence Report. Most municipal supplies report non-detect or trace levels well below the 0.075 mg/L MCL.
Private well owners near landfills, chemical manufacturing facilities, or known industrial contamination sites should request a VOC panel that includes 1,4-DCB. The compound often appears alongside its isomer 1,2-DCB and other chlorinated benzenes in contaminated plumes.
The fix
How AquaOx filters it
Activated carbon is the EPA's recommended best-available technology for filtering 1,4-dichlorobenzene from drinking water. The Centaur catalytic carbon and coconut shell activated carbon stages in The AquaOx adsorb the compound efficiently, with independent testing showing high reductions across the chlorinated benzene family.
Whole-house filtration also reduces inhalation exposure from showers and baths, which matters for volatile compounds like 1,4-DCB.