Common problem · Buda, Kyle & San Marcos
Why does my water smell like rotten eggs?
That sulfur smell is almost always hydrogen sulfide gas, and the fix depends on where it's forming. If only hot water smells, it's usually your water heater's anode rod. If it's one sink, it's likely the drain. If it's all water, it's the supply. A five-minute test tells you which.
Three sources, three fixes
Hydrogen sulfide is the classic rotten-egg gas, and it can enter the picture in three places. In the water heater, the factory anode rod (a sacrificial metal rod that protects the tank) can react with sulfates in our water and generate the smell, which is why so many cases are hot-water-only.
In a single sink, the smell usually isn't the water at all. It's biofilm in the drain releasing odor when water hits it. And when every tap smells, hot and cold, the gas is arriving with the supply, which is common on private wells and rare on city water around here.
Try this first
The honest, cheap stuff
Before anyone sells you equipment, locate the source. It takes five minutes and often the fix is cheap.
The glass test
Fill a glass at the suspect tap and walk to another room before smelling it. If the glass is fine, the smell is the drain, not the water. A drain brush and enzyme cleaner beat a filtration system by a few thousand dollars.
Compare hot against cold
Run cold only, then hot only, and smell each. Hot-only smell points at the water heater's anode rod. Swapping it for an aluminum-zinc rod is a routine plumbing job and usually ends it.
Flush a neglected heater
A heater that's sat unused, like in a rental or after a vacation, can grow sulfur bacteria. Flushing the tank and running it hot often clears that case.
Check every tap
If hot and cold both smell at every fixture, note it. That's the one case where the supply itself is carrying the gas, and it's the case worth testing properly.
The lasting fix
When the supply itself is the problem
If the smell arrives with the water at every tap, the answer is filtration with media matched to the level of hydrogen sulfide in the water. Sizing that correctly starts with measuring it, which is part of what we test.
We'll be honest with you here. On municipal water in Buda, Kyle, and San Marcos, true supply-side sulfur is uncommon, and we'll tell you if your case looks like an anode rod or a drain instead. Private wells in the county see it more often, and a test tells you what you're working with either way.
Questions
Questions we get all the time
Is the rotten egg smell dangerous?
At the levels homes encounter, hydrogen sulfide is a nuisance, not a health hazard. Your nose detects it far below any level of concern. The exception worth acting on fast is a strong sewage smell, which means a drain or venting problem for a plumber, not a water-quality issue.
Why does only my hot water smell?
That's the signature of the water heater's magnesium anode rod reacting with sulfates in the water. A plumber can swap it for an aluminum-zinc rod, usually in under an hour. It's one of the cheapest fixes in all of water treatment, and no, you don't need a filtration system for it.
Will a water softener remove the smell?
No. Softeners exchange hardness minerals, and they don't remove gases. A standard softener won't touch a sulfur smell, so make sure whoever you're working with tests for the actual cause first.
Why does it come and go?
Sulfur smell varies with water use, heater temperature, and how long water sits in the lines. A guest bathroom that only smells after a quiet week is usually just stagnant water or a dry drain trap. Run it regularly and it often resolves.
Smell something? Let's find the source
The free water test covers the smell checklist too: hot versus cold, tap by tap, and what's in the supply. You'll leave knowing which of the three cases you have.
What you get
- Hardness, chlorine, iron, and TDS tested at your tap
- Results explained in plain English, yours to keep
- A recommendation sized to your home (only if you want one)