Hot water smells like rotten eggs? It's probably your water heater
Cold water fine, hot water stinks? Here's why.
If only your hot water smells, the cause is usually inside the water heater: the anode rod reacts with bacteria in the tank and makes the gas. When we install your softener or water system, our plumber checks your anode rod and swaps it if needed, so the smell doesn't follow you. [Confirm whether the swap is included or quoted.]
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You're probably on this page because:
- The cold water smells fine, but the hot water doesn't
- The smell is worse after you've been away
It's usually the water heater, and it's fixable.
Rotten egg smell, by the numbers
- Hydrogen sulfide: the gas behind the smell; harmless at those levels but unpleasant.
Sources: CDC/EPA general guidance.
Why only hot water smells
The water heater's anode rod reacts with bacteria in the tank and makes hydrogen sulfide.
The fixes
- Swap the anode rod for aluminum-zinc or a powered anode
- Flush the tank
- Check the temperature setting
When it's the water instead
If cold water smells too, it's your supply, usually a well.
Life with it vs. without
| Without it | With it |
|---|---|
| Guessing what's in your water | Knowing, and fixing it |
Our take
Why softened water can make it worse
We've answered this question thousands of times, on calls, on installs and for the water companies we supply.
Softened water can speed up the anode rod reaction in some water heaters, so the smell can show up after a new softener. That's not the softener being bad; it's the rod.
That's exactly why our plumbers check the anode rod on every softener install. Fix the rod, and you get soft water without the smell.
Written by people who install these every day
20+ years in water. No fluff, just how it really works.
- 20+ years in water
- Our own patents
- We supply other water companies
- [Thousands] of systems sold
- Licensed installers
Written by [Name], [title], [20+] years in water treatment. Reviewed by [Licensed plumber name], license # [#]. Last updated [date]. Sources: listed under each "By the numbers" block and linked in the copy
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Questions people ask
Why does my hot water smell like rotten eggs?
Usually the water heater anode rod reacting with bacteria.
Is it dangerous?
At typical levels, no, just unpleasant.
How do I fix it?
Swap the anode rod and flush the tank.
Will a softener cause this?
It can make it more noticeable; the rod is the fix.
Why is it worse after vacation?
Water sat in the tank.
Can you fix it?
Yes, our plumbers check the rod on every install.