House Smells Like Rotten Eggs When It Rains? (We Have a Fix!)

Rainy weather can be relaxing if you’re at home, that is until your house smells like rotten eggs afterward. It can come as a shock when you notice sewer odors in your home, especially right after a peaceful rain. So, why is it that your house smells like rotten eggs when it rains?

The most common reason that a house smells like rotten eggs when it rains is that sewer gases rise upward. Air becomes heavier when it rains and the rainwater pushes dense sewer gases to the top. Downdrafts from cold wind can also make your house smell like rotten eggs when it rains and so can a blocked sewer vent.

An unused bathroom can make your whole house smell like rotten eggs because the P-trap can dry out. Sewer odors are dangerous to breathe in, so it’s important to identify and treat the cause. Follow along as we explore why your house smells like rotten eggs when it rains.

The main reason that your house smells like rotten eggs when it rains is that rainwater pushes sewer gases within your septic tank upward. The gases in a septic tank have a much lower density than rainwater. Rainwater eventually pushes the sewer gases upward as pressure increases within the tank.

This can cause your house to smell like rotten eggs or sulfur, but all that you smell is sewer gas. The atmospheric pressure changes and makes the air within the septic tank much heavier. Between the heavy hair, rainwater, and low-lying sewer gases, it is the perfect storm for your house to smell like rotten eggs when it rains.

However, not every homeowner has a septic tank, but you may still notice that your house smells like rotten eggs when it rains. It is more common for your house to smell like rotten eggs after it rains if you have a septic tank, but there are several other possible causes such as a downdraft or blocked vent.

Rain makes the air heavier, and this heavy air can negatively affect your sewer system’s ability to vent gases. Your house may also smell like rotten eggs when it’s not raining if your vents are clogged or blocked. It is easy to accidentally block important vents when you perform landscaping maintenance.

The rotten egg smell may be strong in your yard as well as in your house. It doesn’t need to rain for your house to smell like rotten eggs, but the heavy air that rain brings makes it harder for your system to vent the odor.

A full septic tank can smell like rotten eggs whether it rains or not. The old wastewater sits in a full septic tank and new water cannot enter it properly. It takes an average of 5 years to fill a septic tank, but it varies based on the dimensions and usage.

The sewer odor will grow stronger until you empty your septic tank. Strong winds and poor weather can stir up the smell and make your house smell like rotten eggs when it rains. That is why you should empty your septic tank immediately when it’s full, and it costs an average of $452.

Downdrafts can explain why your house smells like rotten eggs when it rains if you don’t have a septic tank. Cold air and wind often accompany rain causing downdrafts that stir up sewer gases. Unfortunately, this is often unavoidable as long as you have a traditional roof vent.

Your house is less likely to smell like rotten eggs during warm, calm weather. That is how you can tell that downdrafts are the problem. This is the best-case scenario, however, because it doesn’t mean that there is a serious issue with your septic system, even if it is unpleasant.

Unused bathrooms can cause your house to smell like rotten eggs at any time. That is because the water within the P-trap can easily dry out and allow sewer gases to emerge. The water in a P-trap keeps sewer odors at bay, but that isn’t possible when it dries out.

It is ideal to flush a toilet several times per week even if you don’t use it. That way, there will always be water in the P-trap and your house won’t smell like rotten eggs. The rotten egg smell can also come from unused shower and bathtub drains.

The most serious reason for a rotten egg smell could be contributed to a gas leak. The leak could be coming from any number of places like your stove or your furnace. Gas companies inject a chemical called mercaptan into residential gas which is normally odorless. This is for your safety and helps to detect any problems.

It is important that you leave the house immediately if you suspect a gas leak and call the fire department. After you’ve ruled a gas leak, these other options might be the cause of the smell.

Well water differs from treated water from a municipal system. Well water is untreated groundwater, and roughly 13 million homes in the U.S. rely on them. If you own a home with well water and smell rotten eggs, it could be coming from a buildup of hydrogen sulfide in the water. This buildup typically comes from vegetation in the ground that has decayed, and it’s not dangerous in small doses.

How to Fix It: To know for sure, you can have your water tested by a state-certified lab. If your water tests positive for hydrogen sulfide, they will be able to guide you through the steps on how to treat it. Usually, they’ll recommend some type of chlorine treatment that reduces hydrogen sulfide production.

If you live in the southern parts of the U.S. in a house built between 2001 and 2009, chances are the rotten egg smell is coming from your drywall. During this period, that region experienced a drywall shortage after a series of hurricanes. Drywall was often imported from China, but that product had extra amounts of sulfur, the smell of which can be released into your home.

How to Fix It: Unfortunately, the only real solution is to replace your drywall. It’s not ideal, but you can always see if your home owner’s insurance will offset some of the costs. Check this out if your house smells like maple syrup.

When is the last time you cleaned out your fridge? The rotten egg smell could quite literally be rotten eggs or other food gone bad. After a gas leak, this might be the first place you check, especially if you’re the worst at cleaning out your fridge.

How to Fix It: The solution is so simple: throw it away! If you have a garbage disposal, you can dump the spoiled food down there with some fresh basil or orange peels to help diffuse the scent. If not, get it in the trash, and get that trash out of your house pronto. Otherwise, it will continue to smell every time you open the lid. If the smell lingers in your fridge, put in a box of baking soda to absorb the odor.

The simplest way to get rid of the rotten egg smell is to run the water in all of your sinks, tubs, and showers. Doing this every couple of months will ensure that none of the p traps will go dry. If you have a basement with drains, it’s recommended that you pour a quart or two of water down them to flush them out.

If you’ve tried this method and are still noticing the smell, something bigger than evaporated p traps might be in play. At that point, it is recommended that you get your septic tank inspected from a credible septic service company.

Related Questions

Can sewer gas kill you?

When inhaled at high levels, yes, it can be fatal. Its effects are much the same as carbon monoxide. Inhaling the gas causes the cells to be deprived of oxygen.

What does carbon monoxide smell like?

Unlike the gasses in your home which are injected with mercaptan to give off a smell, carbon monoxide has no odor. You won’t be able to detect it without the use of a carbon monoxide detector. It’s most important that you have a properly functioning carbon monoxide detector in your home as this gas is dangerous and even deadly.

Why does my car smell like rotten eggs?

If your car smells like rotten eggs, it might be that your fuel system has a malfunctioning part. This would cause the sulfur-smelling gas to make its way into your car. In order to fix the problem, the part would need to be repaired.

From evaporated p traps to well water and even—yikes!—a gas leak, there are a plethora of reasons why your house might smell like rotten eggs when it rains. It can even smell that way if it’s not raining! But just as there are a lot of reasons for the smell, there are also many ways to get rid of it.

It could be something as simple as running water every so often to keep water in the p traps. Or it could be a bit more complicated, and an expert may need to be called in to assist. Either way, you won’t have to endure that awful smell forever!