HYDROGEN SULFIDE & ROTTEN EGG SMELL IN WATER

rotten egg smell in water

Rot­ten egg smell is a com­mon water qual­i­ty issue in the New Eng­land region usu­al­ly caused by Hydro­gen sul­fide. Hydro­gen sul­fide is a col­or­less gas that can exist nat­u­ral­ly in ground­wa­ter. Sul­fur-reduc­ing bac­te­ria present in ground­wa­ter use sul­fur as an ener­gy source to chem­i­cal­ly change sul­fates to hydro­gen sul­fide which releas­es a rot­ten egg smell in water. The bac­te­ria use sul­fur from decay­ing plants and oth­er organ­ic mat­ter in oxy­gen-defi­cient envi­ron­ments. They can occur in deep or shal­low wells, and reside in plumb­ing sys­tems. Hydro­gen sul­fide can reveal itself in oth­er ways too. Hot water heaters that have a mag­ne­sium rod used for cor­ro­sion con­trol can chem­i­cal­ly reduce sul­fates to Hydro­gen sul­fide.

Hydro­gen sul­fide also can enter sur­face water through springs as well. It is most com­mon in shale and sand­stone. The occur­rence of Hydro­gen sul­fide gas has been asso­ci­at­ed with ground­wa­ter with low pH and/or ground­wa­ter with high lev­els of iron and/or man­ganese (typ­i­cal water qual­i­ty issues in New Eng­land). Hydro­gen sul­fide has a pun­gent smell at low con­cen­tra­tions and most peo­ple can detect con­cen­tra­tions above 0.03 ppm. There is no Max­i­mum Con­t­a­m­i­nant Lev­el estab­lished by the Unit­ed States EPA.

DOES HYDROGEN SULFIDE POSE A HEALTH RISK OR IS THE ROTTEN EGG SMELL IN WATER JUST AN AESTHETIC ISSUE?

Usu­al­ly it is not a health risk at con­cen­tra­tions present in house­hold water.  How­ev­er, Hydro­gen sul­fide gas is flam­ma­ble and poi­so­nous at high con­cen­tra­tions. Buildup of Hydro­gen sul­fide con­cen­tra­tions in con­fined areas has been known to cause adverse health effects.  For more on this, see the link at: OSHA H2S Link.

Bac­te­ria in ground­wa­ter are respon­si­ble for most of the sul­fide smells detect­ed while sam­pling water wells. These are not often asso­ci­at­ed with high enough con­cen­tra­tions to be a health issue. In rare cas­es, sul­fide pres­ence may be due to sewage pol­lu­tion. If you expe­ri­ence a rot­ten egg odor sud­den­ly, con­sult with a water fil­tra­tion sys­tem pro­fes­sion­al.

OTHER AFFECTS OF H2S

Oth­er than releas­ing a rot­ten egg smell in water, Hydro­gen sul­fide may be cor­ro­sive and can leach met­als from plumb­ing sys­tems into the water. The result of this cor­ro­sion of met­als by Hydro­gen sul­fide can be a black pre­cip­i­tate that can stain laun­dry and bath­room fix­tures, dark­en sil­ver­ware, and dis­col­or cop­per and brass uten­sils.  Also, at high lev­els, Hydro­gen sul­fide can pose seri­ous health threats.  For more on this, see the link at: OSHA H2S Link.

H2S REMOVAL TECHNOLOGIES & SYSTEMS

While there are sev­er­al tech­nolo­gies avail­able to remove the rot­ten egg smell in your water, it can­not be viewed in a vac­u­um. The pH lev­el, iron & man­ganese lev­els, as well as oth­er con­t­a­m­i­nants present in the water must be eval­u­at­ed for an effec­tive, com­pre­hen­sive solu­tion to this issue. Some of the tech­nolo­gies and sys­tems that may be used include:

 

  • Ozone treat­ment cre­ates a chem­i­cal reac­tion that pre­cip­i­tates sul­fur. Ozone is effec­tive for con­cen­tra­tions up to 10 ppm.
  • Oxi­diz­ing fil­ters will work for con­cen­tra­tions up to 6 ppm. The fil­ter con­tains sand with a man­ganese diox­ide coat­ing that changes hydro­gen sul­fide gas to tiny par­ti­cles of sul­fur that are trapped inside the fil­ter.
  • Acti­vat­ed car­bon fil­ters can be effec­tive when hydro­gen sul­fide is present in low lev­els (up to about 0.3 ppm). The hydro­gen sul­fide is absorbed onto the sur­face of the car­bon par­ti­cles. Fil­ters require peri­od­ic replace­ment and can har­bor sul­fate-reduc­ing bac­te­ria
  • Shock chlo­ri­na­tion of your well may reduce the hydro­gen sul­fide-pro­duc­ing bac­te­ria. It’s most effec­tive in water with a pH between 5 and 7 and inef­fec­tive in alka­line (high­er pH) water. An acti­vat­ed car­bon fil­ter may be nec­es­sary to remove resid­ual chlo­rine or small amounts of remain­ing hydro­gen sul­fide.
  • Water heater mod­i­fi­ca­tion is nec­es­sary when hydro­gen sul­fide is caus­ing an odor with­in the water heat­ing sys­tem. Replac­ing the mag­ne­sium cor­ro­sion con­trol rod with one made of alu­minum or oth­er met­als usu­al­ly improves the sit­u­a­tion, how­ev­er, you should check the manufacturer’s war­ran­ty on the water heater to make sure you aren’t void­ing the war­ran­ty.