My Water Smells Like Rotten Eggs, What Can I Do?

A rotten egg smell coming from water is a popular problem. The good news is that it’s often not a health issue, but it can still be off-putting, especially if you aren’t used to it. This article will walk through the smell, the water’s taste, the causes, and what can be done about that rotten egg odor.

Why Does My Water Smell Like Rotten Eggs?

Rotten eggs smell like sulfur, more specifically Hydrogen Sulfide. This is a smell that many of us are familiar with, either from stink bombs or actual rotten eggs, or natural sources like the sulfur water springs that occur naturally in places like Soufriere on the volcanic island of St. Lucia. Hydrogen sulfide is getting into your water, but the real question is, how is it getting there?

Note hydrogen sulfide can be toxic at higher levels as well as flammable, so if you believe this issue to be serious then talk to your local government and/or a water professional immediately.

Diagnosing Hydrogen Sulfide in Your Water

In order to determine why the rotten egg smell/taste is happening, you need to make a few simple observations. The big question is this: Does the sulfur smell happen when your running water is hot, cold or both?

If the smell only happens when your water is cold and it goes away after the water has been running for a few seconds, then you likely have a problem with sulfate-reducing bacteria (SRB). These bacteria consume sulfate and output hydrogen sulfide, depositing it in your water. When this happening in your pipes (or nearby pipes) the sulfide can vent into your water stream. You can consult a water professional or buy a test kit in order or confirm the presences of the bacteria. If the bacteria is present your home might been a chlorination treatment your you might be able to run your hot water heater at an elevated setting in order to kill off the bacteria (assuming they are isolated to that place, which may not be the case).

If the smell only happens when your water is hot then the source of the smell is likely your hot water heater. The heater has a part called an “anode” that is designed to corrode more quickly than the surrounding parts of the water tank. The anode is sacrificed, depositing electrons into the water tank environment so that critical parts don’t themselves corrode. Most anodes are made of magnesium which is more prone to producing sulfur smells as it decays, so replacing a magnesium rod with an aluminum one is often a quick fix. If the smell happens with an aluminum rod then other solutions are possible, like not using an anode at all — though this will shorten the life of your water tank — or remove the sulfides later in the process through use of a de-alkalizer.

If the rotten egg smell is happening in both hot and cold water temperatures and doesn’t decrease with a few seconds of running the water then the hydrogen sulfide could be coming from the water source. This is the case when you will likely need some sort of filtration in order to improve your water’s smell and taste. The type of solution will depend on the seriousness of the issue and how much water you use (both how much you need at a give time and the total need each day).

How Do I Fix My Water’s Rotten Egg Smell?

Assuming your sulfur issue is a result of groundwater (if it’s from your hot water heater then that’s easily addressable), there are corrective actions you can take. The best source of information we’ve found on this is the State of Minnesota.

If you have low levels of hydrogen sulfide then an activated carbon filter will help. This is an aesthetic (that is, taste and smell, not health) issue that can be fixed with filtering. Low levels are typically defined as an amount under 1 mg/L (milligram per liter). These filters are simple, predictable, and relatively affordable. This can be a quick fix for your drinking water, but won’t address showers or bathroom faucets.

If you have moderate levels (generally under 6 mg/L or lower, though some estimates say up to 10 mg/L) then you’ll want to look into an oxidizing filter. One form of these filters is a “manganese greensand” filter but it’s also called an iron removal filter. These filters are generally used for the reduction of manganese and iron, and they are not particularly cheap and required fairly frequent maintenance (to regenerate the compound inside). They are also very effective at reducing arsenic from water.

If you have high levels (above 6 mg/L) then water treatment, likely with chlorine might be necessary. This can happen in the form of a oxidation-filtration system which is designed to oxidize the hydrogen sulfide, turning it to sulfur, and then treating it with a greensand filter or a settling tank. The chlorination of the water (through chlorine bleach and a chemical feed pump) can later be reduced with a de-chlorinating carbon filter or activated charcoal filter.

Other notes:

  • If you use a well, digging another (possibly deeper) well will likely not help the situation, through it could be worth exploring
  • A water softener will not help this situation and will not remove or neutralize the hydrogen sulfide. These devices remove minerals, like calcium, but they won’t help here.
  • Aeration of the water might seem like a good idea but it won’t help with the rotten egg smell.

Now read: How to Choose a Water Filter