Sulfate-Reducing Bacteria

Understanding Sulfate-Reducing Bacteria in Groundwater Wells

If you’ve ever caught a whiff of a rotten-egg smell coming from your groundwater, you’ve likely encountered the effects of sulfate-reducing bacteria (SRB). These naturally occurring microbes can be found in many aquifers, especially in areas like North Dakota, where groundwater often contains elevated levels of sulfate.

🦠 What Are Sulfate-Reducing Bacteria?

Sulfate-reducing bacteria are anaerobic microorganisms—they thrive in environments without oxygen. Their energy comes from breaking down sulfate (SO₄²⁻) present in the water. In doing so, they produce two main byproducts:

• Hydrogen sulfide gas (H₂S) – responsible for the rotten-egg smell

• Organic acids – which can contribute to corrosion and well damage

🛑 Why Are They a Problem?

While invisible to the naked eye, sulfate-reducing bacteria can cause serious operational issues in water wells:

• Hydrogen Sulfide Odor

  
  

  The gas gives off a distinct sulfurous smell that’s unpleasant and can make water unpalatable or unsuitable for some uses.

• Corrosion

  
  

  The organic acids and hydrogen sulfide can corrode metal components in pumps, pipes, and casings.

• Clogging and Biofilm Formation

  
  

  These bacteria often live beneath scale (mineral buildup) and in biofilms, creating thick layers that reduce water flow and harbor even more bacteria.

🧬 Why Are They So Hard to Eliminate?

Their ability to survive in low-oxygen environments makes SRBs harder to kill than aerobic bacteria. They often hide behind scale or slime layers inside the well where disinfectants and oxygen can’t easily reach them. This makes standard disinfection techniques less effective.

💡 What Can Be Done?

Dealing with sulfate-reducing bacteria requires a targeted rehabilitation plan:

1. Mechanical cleaning to remove scale and biofilm where the bacteria hide.

2. Chemical treatment using oxidizing agents that penetrate low-oxygen zones.

3. Regular maintenance and monitoring to keep bacterial populations in check.

🔍 Final Thoughts

Sulfate-reducing bacteria are part of the natural ecosystem in many groundwater supplies. While their presence doesn’t always mean trouble, when conditions are right, they can significantly reduce well performance and water quality.

Understanding their behavior—and designing a well maintenance plan accordingly—is the best way to stay ahead of problems.

For advice on managing sulfate-reducing bacteria in your well or bore, contact the team at Aquabiotics Industrial.