Why Does My Water Smell Like Rotten Eggs?

What causes the rotten egg smell in water?

Hydrogen sulfide. Sulfur reducing bacteria are ordinary organisms that metabolise sulfur compounds and release the gas as a byproduct, and Connecticut groundwater gives them plenty to work with. They are not the same thing as iron bacteria, which produce slime and staining rather than a strong odor, and the two get treated differently, which is one reason a nose alone is a poor diagnostic.

Where the bacteria live is the whole question, because it decides the fix. They settle in the well's water column, in seldom used branches of household plumbing, and very commonly inside the water heater, where warmth and a magnesium anode rod give them everything they need. These are ordinary organisms doing an ordinary thing: sulfur-reducing bacteria, which are not a regulated contaminant, are a nuisance species with a memorable calling card rather than a line a laboratory reports against a limit.

The human nose registers hydrogen sulfide at parts per billion. That sensitivity is why a smell that fills a bathroom represents a genuinely tiny quantity of gas, and why the smell usually arrives long before anything else about the water changes. It is also why the smell is worth taking seriously as information: something changed in the well, the plumbing, or the heater, and the smell is the first instrument that noticed.

Sulfates in the water are the raw material. CT DPH includes both odor and sulfate in the basic indicator panel it recommends every private well run each year, and lists an applicable drinking water standard for odor of less than 2. EPA separately lists odor as a secondary standard at a threshold odor number of 3, one of the non-enforceable guidelines it publishes to help water systems manage aesthetic considerations such as taste, color and odor. Hydrogen sulfide itself is an aesthetic problem covered by taste and odor guidance, not a regulated contaminant.

Why does only one faucet smell?

A single fixture smell is a local problem. The candidates are a branch line that gets very little flow, a colonised aerator, or, very often, the drain rather than the water. This is where the sewage smell searches usually land: a shower that smells of sewage when it runs is more often a dry or fouled trap and a biofilm in the drain than anything arriving through the pipe.

There is a two minute test that separates the two. Fill a glass at the fixture, carry it to another room, and smell it there, away from the drain. If the glass smells, the problem is in the water. If the glass does not, the problem is in the drain, and no water treatment system will change it. Do the same at the kitchen tap and at an outside spigot if you have one, because a spigot usually comes off the line ahead of the heater and the softener, which makes it the most honest tap in the house.

How is hydrogen sulfide measured in a water test?

At the tap, during the visit. Hydrogen sulfide off gasses from a sample quickly, so a bottle that spends a day in transit can read lower than the water in your kitchen actually is. That is why the odor and the related field chemistry are measured on site while the rest of the panel travels to a Connecticut certified laboratory.

Three numbers decide the equipment: the measured sulfide level, the pH, and the household flow rate. pH matters because it changes what an oxidising media can do, which is why a sulfur visit measures it rather than assuming it. Iron and manganese come off the same report, and they matter too, because the same filter often has to handle more than one thing. Our $299 standard test covers pH, odor, sulfates, iron and manganese along with 17 other parameters on one visit, so the sizing conversation starts from a full page rather than from one reading.

A smell is also a good moment to catch up on the rest of the panel. A private well has no utility behind it, so the sampling schedule belongs to the owner, and an odor complaint is the most common reason a well that has not been sampled in years finally gets sampled. Hydrogen sulfide often travels with other chemistry worth knowing about, including low pH and iron, and how often to test a well sets out the schedule the rest of the year runs on.

How Bedrock diagnoses it in one visit

We start at the taps, not at the well. Hot against cold, first draw against running, fixture by fixture, indoors and outside, because the pattern is the diagnosis and it takes ten minutes to establish. Field measurements catch what a shipped bottle cannot, and the visit measures the pH and related chemistry that decide which media suits the job.

If the pattern points at the heater, we say the fix is a part and not a system. If it points at the well, the sizing math uses your measured numbers and your household flow, and the equipment slots into the treatment train ahead of any softener. Either way the report comes back in 3 to 7 days and we read it with you line by line.

Sulfur odor is the finding most often dismissed as just how the water is around here. It is not. It is chemistry with an address, and it is among the most satisfying problems to fix, because the result is obvious at every tap the same week.