Updated Nov 1, 2022
Tap water that smells bad leaves many homeowners wondering whether their water is safe to drink, cook with, or wash with. With scents ranging from chlorine to rotten eggs, bad-smelling tap water originates from a number of sources. Most aren’t dangerous to your health, but it’s still good to be aware of the causes and know when to seek testing or further advice. Read on to learn why your tap water smells bad.
Salty water is typically caused by high amounts of chloride or sodium in the water, but can also be caused by sewage or salt water getting into the water supply. If you notice a salty taste in your water supply you should contact a local authority for testing, as this can be harmful to health, especially for people with sodium restricted diets.
No matter what type of smell you detect, it’s a good idea to contact a local water authority and have the water tested if you’re feeling concerned. Even if the water turns out to be safe to consume, you will at least have the peace of mind knowing that you made an effort to check.
You might notice a musty, sewer, or egg-like odor if there’s bacteria growth in your water heater, sink, or drain. This is most common when the sink hasn’t been used in a while or in the summer months when temperatures and humidity are higher.
If the smell is coming from the sink or drain:
A rotten egg smell can also be caused by a hot water heater running at a low temperature, or the presence of hydrogen sulfide gas in the water. In the case of hydrogen sulfide gas, this smell will usually become noticeable if the water comes in contact with organic matter or certain minerals.
This smell is most common in water that filters through rock and organic materials (sometimes called hard water). This isn’t harmful to your health, but it’s still not a bad idea to have your water tested when you first notice a change in smell.
If the smell has an earthiness to it, the scent could be caused by algae blooms in the water source.
If your tap water smells a bit like a swimming pool, it’s possible that the water has high levels of chlorine. Many water sources use chlorine to treat the water as a disinfectant, so this smell isn’t uncommon. It is safe to drink water containing standard levels of chlorine, but testing may be a good idea if the smell is stronger than usual. The smell of chlorine will typically dissipate after running the faucet for a few minutes.
If your water has a metallic smell or taste, it could be caused by corrosion in copper piping that’s used for your home’s plumbing. Copper in water typically doesn’t present a health risk until it reaches levels higher than 1,300 parts per billion. You can buy water test kits to check for the presence of metal in your tap water, but some kits test for different metals and elements, so read the description carefully.
Running the tap for 30–60 seconds before drinking is sometimes helpful for reducing this copper taste.
Other reasons for metallic-tasting water are high zinc levels and dissolved minerals containing sulfates. Neither are particularly harmful, but sometimes the sulfate-containing minerals will cause a mildly laxative effect on people who aren’t used to it.
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