Testing for and Removing Hydrogen Sulfide

If you’ve experienced foul “rotten egg” or sulfur odors in your water, it may be that your water is contaminated with high levels of hydrogen sulfide or methane gas.  At low levels, these gases are generally harmless.  At high levels, however, they are at best a nuisance and at worst, a serious health concern.  

While there is no drinking water quality standard for hydrogen sulfide in water, there is a Secondary Maximum Contaminant Level set for odor in drinking water, which, as mentioned, is a symptom of hydrogen sulfide contamination.  This SCML, according to the EPA, is 250 mg/L (or parts per million).

Hydrogen sulfide, otherwise known as H2S, is flammable and poisonous, and can be toxic if ingested in excess.  The release of H2S gas in a confined area can cause nausea, illness, and in extreme cases, even death.  When dissolved in water, H2S can corrode plumbing metals such as steel, copper, and brass, as well as exposed metal parts in washing machines and other appliances.  When corroded by hydrogen sulfide, iron and steel will form ferrous sulfide or “black water,” which can darken silverware and discolor copper and brass utensils.

water_heater6Hydrogen sulfide gas may be naturally present in wells drilled in shale or sandstone, near coal or peat deposits, in oil fields, and in sewage.  It can also enter surface water through springs, and from there escape into the atmosphere.  Your water heater is also a likely source of H2S odors, as the magnesium rod commonly used in heaters can chemically reduce sulfates to H2S.

In well water, hydrogen sulfide is commonly released by iron and sulfur bacteria that chemically change sulfates into H2S gas as a byproduct of their biological processes.  They use the sulfur from decaying plants, rocks, or soil, and often thrive in iron-rich and oxygen-deficient environments – in other words, your well.  Although these bacteria are generally harmless to your health, they will continue to create foul odors and tastes unless destroyed completely via chlorination, peroxide injection, ozonation, or aeration.

Well Test Pro II Kit

Testing for hydrogen sulfide is not always necessary, as it can usually be easily detected due to its smell and taste.  However, to ascertain a quantitative measure of H2S presence in your water, a lab test will indeed be necessary.  Our Well Test Pro Kits (both I and II) come with 2 hydrogen sulfide tests each, a bacteria test, and a prepaid mailer for sending your sample in to our lab.  If you suspect sewage pollution is the source of your H2S, be sure to test your water for coliform bacteria as well.

After you’ve confirmed H2S contamination, the next step is to seek corrective action. As mentioned above, the most common options for destroying iron and sulfur bacteria are:

  • chlorination
  • aeration
  • peroxide injection
  • ozonation

For more on well water odors, read our odors guide.  Also,  browse our selection of chlorinators (which can also be used for peroxide injection), ozone systems, and aerators on our website.  For further help testing for or correcting well water problems, e-mail us at support@cleanwaterstore.com, drop us a line on Facebook, or use our online contact form.

About the Author Gerry Bulfin

Need help with your well water? I have been assisting homeowners, small communities and businesses improve their well water quality since 1989. Please email me at gbulfin@cleanwaterstore.com if you have a question about water testing, test kits or well water systems in general. Gerry Bulfin CWS-IV Master Water Specialist WQA Certified Licensed California Water Treatment Contractor