My Water Smells Like Rotten Eggs!

There may be sulfur in your water, here's what to do...

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Have you ever turned on your faucet and been hit with the smell of rotten eggs?

The culprit is sulfur. While it’s definitely a nuisance, this unpleasant smell is not usually indicative of any health risks at the concentrations found at your tap.

Types of Sulfur Found in Drinking Water

There are two forms of sulfur that are generally found in tap water: sulfate and hydrogen sulfide.


A combination of sulfur and oxygen, sulfates are a part of naturally occurring minerals in some soil and rock formations that contain groundwater. Over time, the minerals dissolve and sulfates are released into the water. Sulfates can be found in man-made hazards, such as landfills, pipelines, old septic systems, or industrial chemical factories.

Hydrogen Sulfide:

While hydrogen sulfide gas is formed as organic matter decomposes underground, the primary producers of hydrogen sulfide are sulfur-reducing bacteria.These bacteria, which use sulfur as an energy source, chemically change the natural sulfates in water in hydrogen sulfide. Sulfur reducing bacteria thrives in oxygen-deficient environments (like landfills and deep wells) and can form in your water technologies (softeners, water heaters, etc).

Indications of Sulfur in Your Water


  • Taste: Because sulfate minerals can cause scale to build up in your pipes, they may cause your water to taste bitter.
  • Smell: Unlike hydrogen sulfide, sulfate does not produce an odor.
  • Stains: Increased sulfate levels, in combination with chlorine bleach, can also make it challenging to clean your clothes. Sulfur-oxidizing bacteria can cause a blackening of water or a dark slime coating the inside of your toilet tank (similar to the staining effects of iron bacteria). If you want to learn more about removing water quality-related stains, take a look at our Stain Guide.

Hydrogen Sulfide:

  • Taste: Elevated concentrations of hydrogen sulfide can alter the taste and appearance of cooked foods and beverages made with water (tea, coffee, etc.).
  • Smell: Hydrogen sulfide gas is the unpleasant rotten egg odor and taste in your water. An odor is detectable by most people at a concentration as low as 0.5 ppm. A concentration of 1-2 ppm is when water begins to acquire a rotten egg odor. It may only be noticeable when the faucet is initially turned on or when hot water is run. This is because the heat volatilizes hydrogen sulfide. So, the rotten egg smell may be particularly bad when you shower.
  • Stains: Because it can corrode metals (like iron, copper, and brass), hydrogen sulfide can tarnish and discolor metal kitchenwares. It may also cause yellow or black stains on your water fixtures.

Potential Health Effects of Sulfur-Water


The main concern with sulfate in your drinking water is dehydration, because sulfate can have a laxative effect. However, with time, those exposed to sulfate become acclimated and symptoms disappear.

Hydrogen Sulfide:

While usually not a health risk at concentrations typically found in household water, hydrogen sulfide is both flammable and poisonous. At very high concentrations of hydrogen sulfide have been known to cause: nausea, illness, and (in extreme cases) death.

Sulfur Levels In Your Water


The Environmental Protection Agency (EPA) has created two categories for drinking water standards. The first, the Primary Standards, are based on health considerations and are designed to protect people from toxic pollutants. The other category, Secondary Standards, are based on taste, color, odor, corrosivity, foaming, and staining properties of water. Sulfate falls under this second category. The secondary maximum contaminant level (SMCL) for sulfate is 250 ppm–although only 3% of water supplies had sulfate levels in excess of this level.

Hydrogen Sulfide:

Hydrogen sulfide is not regulated under the Primary or Secondary Standards. A concentration high enough to be a drinking water health hazard also makes it unpalatable, so it would not likely make it to your tap. Generally, hydrogen sulfide levels are less than 10 ppm, but have been reported as high as 75 ppm.

How to Treat Sulfur-Water:


While several methods are available for removing sulfate from your drinking water, the best choice depends on several factors including:

  • The concentration of sulfate in the water
  • The amount of iron and manganese in the water
  • If there is bacterial contamination
  • How much water you need to treat

For treating small quantities of water, the most common methods are distillation or reverse osmosis. For large quantities, the typical method is ion exchange.

Hydrogen Sulfide:

In order to remove low levels of hydrogen sulfide that DO NOT include bacterial problems, the best solution is an activated carbon filter. Replace the filter periodically to maintain functionality. For concentrations up to ~5 to 7 ppm, hydrogen sulfide can be removed using an oxidizing filter. If your water has concentrations exceeding ~7 ppm, hydrogen sulfide can be removed by injecting an oxidizing chemical (i.e. household bleach or potassium permanganate) followed by filtration.

Are You Concerned About Your Drinking Water?

If you tap water tastes, looks, or smell funny, our TapScore home water testing package can give you some answers. Our national team of certified laboratory scientists, engineers, and health experts provide each customer with a personalized Tap Score Water Quality Report. For more information, message us.