Groundwater as a Source of Hydrogen Sulfide in Indoor Air in Central and South Florida

Abstract

Groundwater in Central and South Florida is known to contain high levels of sulfide. A series of shower tests were designed to evaluate hydrogen sulfide (H2S) emissions from sulfide-containing groundwater in residential houses. To our knowledge, indoor H2S levels resulting from regular household usage of water containing sulfide have never been studied or compared to that generated by other sources, such as defective drywall. Our objectives were to determine the factors controlling H2S emissions during a shower; to evaluate indoor H2S levels associated with regular household water usage; and to apply a one-box model to predict indoor steady-state H2S concentration. Shower tests conducted under controlled conditions indicated that pH has a significant impact on emission rate, whereas temperature does not. Both pH and temperature significantly impacted emission percentage. Flow rate and total sulfide concentration in water significantly impacted emission rate, but not emission percentage. Shower tests conducted at six residential houses located in five cities indicated that H2S in the air increased linearly with time during the shower-testing period. A 3- to 20-min shower—using water with total sulfide concentrations ranging from 0.20 to 2.45 mg/L—raised H2S concentrations in the bathroom air to 300–2250 parts per billion by volume. The indoor steady-state H2S concentration caused by regular household water usage can be predicted with a one-box model. Our study suggested that, without proper treatment, groundwater containing high concentrations of sulfide can be a significant source of H2S in indoor air.