Why Does My Well Water Smell Bad? Top 4 Odors and Their Causes

infographic why does my well water smell bad

If you’re like most homesteaders on well water, you probably take it for granted. You turn on the faucet and out comes clean, refreshing water – no need to worry about it! But what if your well water starts smelling bad like rotten eggs? Suddenly, you’ve got a whole new issue to deal with: why does my well water smell bad? Here are the top four common odors you may smell in your well water and what causes them.

1. My well water smells like rotten eggs

Just like I mentioned at the beginning, your well water might suddenly smell distinctly like rotten eggs. The cause is likely sulfur bacteria that have made their way into your well. In low oxygen environments like wells, hydrogen sulfide gas can form, which is where the bad smell is coming from.

Before you go any further, we recommend you go through a bit of troubleshooting to narrow it down and make sure the smell isn’t coming from just a few faucets or taps. Try running your hot water only – is the smell worse? Compare a glass of hot water to a glass of cold water. If the smell is coming from the hot water, the problem is likely bacteria in your water heater. If certain faucets smell bad and certain others don’t, the problem is likely bacteria in some specific plumbing. If it doesn’t make a difference and the smell is always there, it is most likely coming from the well itself.


If the problem is in the water heater, have a plumber or other professional come in and replace the magnesium anode and/or have them disinfect and flush the heater with a chlorine bleach solution. If the problem is in certain plumbing areas, have them disinfect the plumbing with a bleach solution. 

If the problem is in the well itself, there are a few things you can do. Since we know that the smelly sulfur gas is caused by a lack of oxygen, one thing you can do to eliminate the smell is to add an aeration system to pump more oxygen into the well. Second, you could look into using an oxidant and water filtration system designed to kill sulfur bacteria. If you are going this route, you should test your water for other contaminants like coliform bacteria, nitrates, lead, VOCs and others to treat any other issues that may be there.

To learn more about sulfur bacteria in wells and different treatment options, this page is a fantastic resource.

2. My well water smells like fish

The most likely reason for a fishy smell in your water is simply naturally occurring organic material breaking down in your water source. Most of the time, it’s harmless despite the off-putting smell. It could signify higher than normal levels of barium and cadmium, which are naturally occurring metals that could make their way into your water supply.

We’ve actually had this one happen to us before. One day when I was doing dishes, I noticed the insides of the glasses smelled slightly gross, almost fishlike. Just a slight off-putting smell. I was worried that there was something majorly wrong with our well water, but it was a relief to learn that it was probably just organic material breaking down. Thankfully, the smell went away by the next day and it hasn’t come back since.


You may not need to treat the problem if it goes away on its own like ours did, but if it persists or if you want to prevent it from happening, a great way to remove contaminants from your well is to install a reverse osmosis (R.O.) water filter for your home. Carbon filters are another good option.

3. My well water smells musty or earthy

If your water has a distinctly musty or earth smell to it, especially if it’s coming from your hot water, it is likely caused by iron bacteria in your water. Iron bacteria use, unsurprisingly, iron as an energy source and can build up in your plumbing and start leaving slimy deposits as well as a musty smell. The presence of iron bacteria often goes hand-in-hand with iron buildup, so you might notice reddish-brown stains in your toilet bowl and sometimes even yellow well water.


Iron bacteria contamination is not known to be particularly harmful to your health, but it can create favorable conditions for other types of bacteria and even lead to clogging in your pipes. If you suspect you have iron bacteria, you should test your water for other contaminants as well including coliform and nitrate bacteria.

The best way to go about treating iron bacteria is with a good iron removing water filter.

4. My well water smells like sewage

Now this is probably the nastiest smell of all! Smelling sewage in your water is enough to make you panic. But hold up! This might be the easiest one to treat.

You might think you are smelling sewage from your faucet, but it could actually just be bacteria or rotting food stuck in your drain, making the whole sink stink!

There is a chance there could be bacteria in your water heater if it was left unused for a long time. Have you just returned from a long vacation? Did you shut off your hot water tank to save energy?


Check to see where the smell is coming from. Fill up a glass of hot water and a glass of cold water, walk away from the sink and smell the glasses. If the water smells normal in both glasses, you know it’s just bacteria in your sink. Fortunately, this is an easy fix and you can treat it right away!

Pour ¼ cup of baking soda down the drain followed by ¼ cup of white vinegar. Let it bubble there for at least 10 minutes. While it’s bubbling, boil some water and pour the hot water down the drain after 10 minutes. This will clear the bacteria and get rid of that nasty smell. This is a perfectly safe method for septic systems, too. If you are on a septic system, make sure to not use bleach in any disinfection procedures and do not pour it down the drain. This can kill the beneficial bacteria in your septic field. And of course, never mix bleach with vinegar or any other cleaning products for the record!


Most of the time, bad-smelling well water fits into one of these four categories. Fortunately, there are ways to deal with each of these odors.  If you are unsure what your water smells like but, but something still doesn’t smell right, we’d recommend calling a local professional to come in and test your water.

Have you had any issues with your well water smelling funny? What was the problem and what did you do to fix it? Let us know in the comments!

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