Foul smells in your water supply can come from a few different places. While these bad odors are usually harmless, they can be indicative of a problem with your water supply or plumbing and are worth looking into. The good news is that these issues are usually easy and inexpensive to fix.
1. Bacteria In the Water
One of the main causes of a foul smell in your water itself is a type of bacteria that smells like sulfur or rotten eggs. This is usually harmless, but the smell can get irritating, so it's worth looking into.
The first thing to check is whether you detect the smell with all running water or only hot water. If you only detect the smell when hot water is running, it's likely that the source is your water heater. This can often happen when the bacteria has a reaction with the materials of your anodes, and can usually be fixed by replacing the anodes with a different kind that won't cause the bacteria to react, such as an aluminum/zinc anode.
If you get the smell all the time, it's probably coming from your water supply itself, and is worth contacting your water company about. They may be able to offer information about the cause of the odor or send someone to investigate for you.
2. Clogged Drain or Vent
One thing that can cause a foul smell in your bathroom is a drain clog. Even if it seems like your drains are working properly, there could be a clog farther down the drain that isn't noticeable unless you run a lot of water. These clogs can collect hair, toothpaste, shampoo, oils, and anything else you put down the drain. This can hold back water from draining, and the bacteria that grows in it can start to cause a smell of rotten eggs. Make sure your drain pipes are clear to prevent this from happening.
It could also be the case that your drain vents aren't working properly. Drain vents help regulate air pressure inside your pipes to keep water draining smoothly, but if a vent isn't working, this water flow could be disrupted, trapping water long enough that it can start to smell.
3. Dry Or Malfunctioning P-Trap
Every drain in your house has what's called a P-trap, which is designed to keep the odor from the sewer or septic tank from coming back up your pipes and into your house. Every time you use a drain, some water will be left at the bottom of the trap, essentially blocking the sewer smell.
If you haven't used a drain in a while, the water in the trap could have evaporated, leaving space for a foul smell to come up the drain. The best way to avoid this is to just run a little water down every drain in your house once a month.
If you notice this smell often even with a sink you use regularly, it could still be because of the trap. It could simply be losing water in other ways. If the trap has a leak, even if only a minor one, this could let the smell in much faster. It's also possible that something could be stuck in the pipes close to the trap that's absorbing water or preventing the water in the trap from making a seal. Check each drain pipe to make sure it's not leaking, and try using a snake to pull out or clear any debris that could be getting in the way.
For more information, contact your local plumbers today.