Hydrogen Sulfide in Household

Janice Woodard, Retired Extension Specialist, Home Management and Equipment Blake Ross, Extension Specialist, Agricultural Engineering Introduction The presence of may be seasonal and frequently occurs in well water which also Hydrogen sulfide gas is a nuisance contains appreciable levels of iron and/or that is not usually a health risk at manganese, or that has a low pH. concentrations present in household water. Water containing hydrogen sulfide, Testing for Hydrogen Sulfide commonly called sulfur water, has a distinctive "rotten egg" odor, which may be especially To determine an appropriate treatment method, it noticeable when running hot water. Such water is necessary to find out how much hydrogen can discolor coffee, tea and other beverages, and sulfide is present in the water supply. Since alter the appearance and taste of cooked foods. hydrogen sulfide is a gas that is dissolved in water and can readily escape from it, determining the Hydrogen sulfide dissolved in water can also concentration of hydrogen sulfide requires that the corrode plumbing metals, such as iron, steel, water sample be tested at the site or be copper and brass and exposed metal parts in immediately stabilized for laboratory analysis. washing machines and other water-using Sample bottles with stabilizing chemical should be appliances. The corrosion of iron and steel from obtained from the laboratory that does the hydrogen sulfide forms ferrous sulfide or "black analysis. These stabilized watersamples water" which can darken silverware and discolor cannotbeanalyzed forothercontaminants. When copper and brass utensils. Hydrogen sulfide can is a suspected source of also interfere with the effectiveness of water hydrogen sulfide, the water should be tested for softeners. coliform bacteria A concentration as low as 0.1 milligrams hydrogen sulfide per liter of water (mg/l ) is Treatment of Hydrogen Sulfide detectable by smell by most people. However, characteristic hydrogen sulfide taste can be Problems detected in water with a hydrogen sulfide The recommended treatment for reducing concentration as low as 0.05 mg/1. hydrogen sulfide varies with its concentration in Sources of Hydrogen Sulfide household water. Select the treatment appropriate for the amount of hydrogen sulfide present in the Hydrogen sulfide gas is formed from decomposing water supply from the following treatment underground deposits of organic matter, such as options: (Where ranges for hydrogen sulfide decaying plant material. This gas occurs in deep or concentrations given below overlap one another, shallow wells and can also enter more than one treatment method may be suitable.) through springs. Hydrogen sulfide from sewage pollution can occur in some surface water, in · Trace amounts of hydrogen sulfide (up poorly constructed wells or in shallow wells close to a few tenths mg/1) to sewer lines or septic systems. Wells drilled in At this level, activated carbon filtration shale or sandstone, or near coal or oil fields often will reduce the unpleasant taste associated have hydrogen sulfide present in the water. with hydrogen sulfide but has a very limited capacity for odor absorption. sufficient storage must be provided to Hydrogen sulfide gas is adsorbed onto the maintain 20 minutes of contact time carbon surface. In this method, the filter, between the water and the chemical. This when exhausted, must be replaced, not process may produce objectionable taste in recharged. the water. Depending upon the amount of · Less than 2 mg/1 hydrogen sulfide chlorine added, an activated carbon filter Aeration (adding air to the water) is an may be used to obtain chlorine-free water appropriate treatment method. In any for cooking and drinking. The sarne carbon aeration system, the water must be filter can also reduce any remaining protected from bacterial contamination and hydrogen sulfide. Maintenance and freezing, and there are large space replacement of filter systems should be requirements. Another limitation of this considered since sulfur, iron, manganese method is that the aeration process and other suspended materials in the water produces a strong hydrogen sulfide odor can quickly clog the filter. near the aerator which may be unpleasant Sulfur Bacteria if near the household living area Furthermore, this process, by itself, may It is possible to have the characteristic "rotten egg" not always reduce the hydrogen sulfide to odor in water even when laboratory tests show the non-detectable levels. However, the absence of hydrogen sulfide. In this case, the odor addition of a carbon filter may remove is caused by harmless bacteria that chemically some of the remaining trace amounts of change sulfate in the water to hydrogen sulfide. hydrogen sulfide. These bacteria live on the hot water side of the home water distribution system. · 1-10 mg/1 hydrogen sulfide The use of an iron-removal filter Shock chlorination of the entire water system, containing manganese greensand is including storage, hot water tanks, and distribution suggested. Manganese greensand filters lines, kills the bacteria. This process introduces must be recharged with a solution of very high concentrations of chlorine into the water permanganate when the oxygen system. Chlorine should remain in the system for is depleted. This process is similar to several hours, preferably overnight. If the situation regenerating a water softener and usually persists, continuous chlorination may be required. must be implemented at intervals from one to four weeks depending on the condition Summary of the water, size of the unit, and amount Hydrogen sulfide in drinking water is a common of water consumption. Water with a pH nuisance contarminant. Although it is not below 6.7 may need to be treated with an hazardous to health, the offensive odor and acid water neutralizer before iron removal corrosivity of household water containing filtration will be effective. hydrogen sulfide make treatment desirable. Although there are various treatment alternatives, · More than 6 mg/1 hydrogen sulfide chlorination is the most commonly used and Constant chlorination using an automatic effective. Often, the treatment for hydrogen chemical feed pump is the most common sulfide is the same as for iron and manganese, treatment method. The recomrnended allowing removal of all three contaminants in one dosage is 2 mg/1 chlorine for 1 mg/1 process. hydrogen sulfide. The chlorine should be added ahead of the mixing tank and

For more information about reducing hydrogen sulfide in household water, contact your local Virginia Cooperative Extension office. The authors wish to thank the following individuals who reviewed this publication: Kathleen Parrott, Extension Specialist, Housing, Virginia Tech Kathryn Sevebeck, Educational Director, Virginia Water Resources Research Center, Blacksburg. Publication Number 356-488, October 1996