Well Water Smells Like Sewage (Here’s Why & How to Fix It)

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Sewage is perhaps the most unpleasant smell coming from anywhere – so if your drinking water has a sewage smell, you’re probably not inclined to drink it.

There are several causes of water smelling like sewage, and some are more dangerous than others. In this guide, we’ll be sharing the most common reasons for a sewage smell in your well water – and, importantly, how to get rid of the smell for good.


A sewage or rotten egg smell is usually caused by sulfur gas or bacteria in your water supply. You can resolve the issue by eliminating the odor at its source, or, if that isn’t possible, installing a water treatment system.

📝 4 Reasons Why Your Water Smells Like Sewage

The four most common causes of a sewage smell in well water are listed below.

1) Bacteria Growing In Your Drain

First, a smell of sewage might not be from your source water at all – you might just think it is.

Do you notice the sewage smell every time you turn on your faucet? This could be because of bacteria growing in your sink’s drain.

Food waste and other organic matter can build up around the plughole and on the walls of the drain, encouraging bacterial growth. This bacteria may produce sulfur gas, which has a characteristic rotten egg or sewage-like smell . Water running down your drain can activate this smell, making it seem like the water itself is causing the smell.

To find out whether your drain is to blame for the sewage water smell, fill a glass of water and take it to another part of your kitchen. Swirl the water in the glass, then smell. If you can’t smell anything from the glass, you probably have an issue with sulfur bacteria in your drain.

Iron stains in water drain

2) Iron, Sulfur, Or Bacteria In Your Water Source

If your drain isn’t to blame, your water source might be the issue after all.

Bacteria or sulfur in your water gives a smell of rotten eggs or sewage. Certain geographical regions naturally have a lot of hydrogen sulfide gas in the ground, which can leach into groundwater supplies and give off a distinctive rotten egg odor.

If harmful bacteria has entered your water source, you might have an improperly located or defective septic system within the well’s vicinity. Your county health department can help you to deal with this issue.

Iron may also combine with bacteria, forming iron bacteria, which is also known to smell like sewage or dirt. Bacterial iron has an orange, sludge-like appearance and a musty smell, and is often found in your toilet bowl and sinks. If your natural groundwater chemistry encourages bacterial iron growth, this may be the cause of the bad smell in your water.

iron bacteria in water

3) Bacteria In Your Water Heater

Noticed that only your hot water smells like sewage or rotten eggs? You might have a problem with bacteria growing in your hot water heater.

If your household water heater’s thermostat is set too low, your hot water is unused for a long time, or the heater is turned off for several weeks, the risk of bacteria buildup is likely. This problem doesn’t usually pose a risk to your health, but it can make your water smell and taste unpleasant.

Organic matter in your plumbing system may also gather inside your hot water tank, giving water a foul smell. Make sure to get your heater serviced as recommended by your plumber to prevent this issue.

Iron bacteria buildup on water heater

4) Sewage In Your Water

Sewage in your water is, thankfully, the least likely cause of a sewage smell. The likelihood of actual sewage contaminating your well water supply is slim, but not impossible.

If you use a septic tank on your property, check that the tank is being properly maintained. You should clean and pump your septic tank once every three to five years, depending on the size of the tank and its usage.

A leaking or overflowing tank, or a tank positioned too close to your well system, could cause sewage to get into your well. This is most likely if your well’s structural integrity is compromised, such as if the well casing is cracked or damaged.

🧰 How to Fix Water that Smells Like Sewage

These five steps should help you to eliminate a sewage smell in your well water, and prevent the smell from returning.

Clean Your Drains

If the sewage water smell is coming from decaying organic matter deposited in your drain, the solution is simple: clean the offending drain.

To disinfect your drain naturally, pour half a cup of baking soda down the drain, followed by half a cup of white vinegar. Leave the solution for up to half an hour, then switch on your tap to wash it away. Repeat this twice a month or whenever you notice an unpleasant smell.

Woman using vinegar and baking soda to clean the drain

Service Your Water Heater

If bacteria in your water heater is giving off a foul odor, hire a professional plumber to service your heater.

The smell of sewage is often caused by an aluminum or magnesium heating rod. When the materials in this rod corrode, they react with the sulfates in the water, converting them into hydrogen sulfide gas. Your plumber may suggest replacing the heating rod to get rid of the smell.

If a buildup of sediment and organic matter has damaged your heater, your plumber may recommend installing a sediment filter to keep these contaminants at bay.

Test Your Water

If you’ve ruled out water heater and drain issues, your next step is to test your water. Conducting a water test will confirm whether or not your household water supply contains certain contaminants that are known to give water a foul odor, like hydrogen sulfide, sulfur bacteria, or bacterial iron.

We recommend using a professional laboratory test to detect these contaminants. Bacteria in your water isn’t only smelly; it can also be dangerous. You want to make sure you’re accurately testing for this contaminant so that you can remove it from your water if necessary.

Tap score water testing kit in front of faucet

Shock Chlorinate Your Well

If testing has detected bacteria in your water, you may need to shock chlorinate your well.

Shock chlorinating a well involves treating the well with a large amount of chlorine or a similar disinfectant, which kills bacteria (and also breaks down iron and sulfur bacteria).

Switch to bottled water and don’t drink your water supply until you have successfully shock chlorinated your well and a further bacteria test produces negative results. After shock chlorinating your well, the chlorine odor disappears usually within a day or two.

👉 Learn more about how to shock chlorinate a well here

Install a Water Filtration System

Finally, the best way to tackle hydrogen sulfide or bacteria in your drinking water source is to install a water filtration system.

Different system types are good for tackling different contaminants. If you have an iron or hydrogen sulfide problem, consider installing an air injection system, which oxidizes sulfur and removes it with a media. If you’re dealing with bacteria, look at chlorine injection systems or UV purifiers, which can kill bacteria and other unwanted microorganisms.

A typical activated carbon filtration system may be able to improve the taste and smell if your water somewhat, but it won’t be able to remove the cause of the bad smell.

taking measurements for whole house water filter install

Check out our best sulfur filter for well water guide for more information 👈

🧠 Why Does Well Water Smell Like Sewage? FAQ

Why does my water smell like sewage?

If your well water smells like rotten eggs or sewage, you probably have a bacteria or hydrogen sulfide issue in your water supply or water heater. You might also have an issue with a nearby septic tank, such as an improperly located septic system. Before blaming your water supply, check to see if the smell is coming from your kitchen sink drain.

Is a sewage smell dangerous in water?

A sewage-like odor generally isn’t dangerous. If your tap water smells like rotten eggs, it most likely contains hydrogen sulfide – which is smelly, but not dangerous. However, sewage can sometimes indicate the presence of bacteria, which may have adverse health consequences.

Why does well water smell like poop?

If your tap water has a musty, earthy, or poop-like smell, it’s likely contaminated with bacterial iron. This usually occurs if your water has high levels of iron. You can get rid of the smell by shock chlorinating your well, then installing an air or chemical injection system as a long-term iron removal solution.

Why does my well water suddenly smell bad?

Your well water might suddenly smell bad if there has been a change to your local geology (due to flooding, an earthquake, or the natural evolution of the soil and rocks), or if your water heater’s anode rod has begun to corrode. If you’ve noticed a sudden change in the quality of your tap water supply, stop drinking water from your faucet while you get a water sample tested.

Is it normal for well water to smell?

Yes, it’s normal for well water to have an odor. Unlike city drinking water, well water isn’t treated before it supplies your home. Depending on where you live, your well water might have a naturally high iron, sulfur, or bacteria content that is giving it an unpleasant smell.

  • Brian Campbell
    President & CEO, CWS, CWR

    Brian Campbell, a WQA Certified Water Specialist (CWS) and Certified Water Treatment Representative (CWR) with 5+ years of experience, helps homeowners navigate the world of water treatment. After honing his skills at Hach Company, he founded his business to empower homeowners with the knowledge and tools to achieve safe, healthy water. Brian's tested countless devices, from simple pitchers to complex systems, helping his readers find the perfect fit for their unique needs.

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