Well Water Odor in Dallas-Fort Worth Homes
A rotten-egg smell from a private well can come from dissolved hydrogen sulfide gas or certain bacteria, and hydrogen sulfide can be in the groundwater naturally. Other smells point to other problems, and in Texas the well owner is the one responsible for testing.
What Causes Well Water Odor
CDC's toxic substances agency says hydrogen sulfide can be naturally present in well water, giving tap water a rotten-egg odor. Groundwater concentrations are generally less than 1 ppm, and CDC puts the level at which people can smell the gas in air at 0.0005 to 0.3 ppm.
EPA's guide for household wells says a rotten-egg odor can come from dissolved hydrogen sulfide gas or from certain bacteria, and USGS describes how sulfate-reducing bacteria produce hydrogen sulfide as a byproduct, a process that generally happens when no free oxygen is available.
Well Water in Dallas-Fort Worth
Unlike city water, a private well comes with no utility report, and no utility tests it for you.
Who Regulates Private Wells in Texas
Not regulated by TCEQ or under the Safe Drinking Water Act · The owner is responsible
TCEQ states that it does not regulate private drinking water wells, and that a private well owner is responsible for maintaining the well and testing the water. EPA adds that private wells are not regulated under the Safe Drinking Water Act.
Two Texas Aquifers
Trinity: central and northeastern Texas · Woodbine: northeast Texas
For wells that draw from these aquifers, the Texas Water Development Board says sulfate and chloride in the Trinity Aquifer tend to increase with depth, and that water quality and yield in the Woodbine Aquifer vary with the depth of the aquifer.
Where the Smell Shows Up
Where and when you notice the smell narrows down where it starts.
Cold Tap
A rotten-egg smell from a cold glass of water points to the well water itself, either hydrogen sulfide gas or bacteria.
Hot Water Only
A smell that shows up in a hot shower but not at a cold tap points away from the well. EPA says that if the smell only comes with hot water, it is likely from a part in your hot water heater.
What Different Well Odors Can Mean
Beyond rotten egg, EPA lists several other smells in its guide for household wells:
- Detergent, with water that foams when drawn: possible seepage from a septic tank into the well.
- Gasoline or oil: fuel oil or gasoline likely seeping from a tank into the water supply.
- Musty or earthy: decaying organic matter in the water.
- Chlorine: excessive chlorination.
How to Check Well Water Odor at Home
EPA recommends testing your well immediately if you notice a change in odor, color or taste, and CDC warns that these changes sometimes mean the water got contaminated. Both agencies also recommend testing every year for total coliform bacteria, nitrates, total dissolved solids and pH.
Before the test, write down three things: whether the smell is at the cold tap, the hot tap or both; whether it comes and goes; and when you first noticed it. That record helps narrow down where the smell starts.
How to Fix Well Water Odor
If the smell only comes with hot water, have the water heater checked before treating the whole well. If it smells like fuel or detergent, test right away, since those odors can mean something is seeping into the well.
Well Water Treatment
EPA's guide links a rotten-egg smell to hydrogen sulfide gas or certain bacteria, and fuel or detergent smells to seepage. Start with a test of your well water, and the well system is matched to the result.
Well Water Odor FAQs
Why does my well water smell like rotten eggs?
EPA says a rotten-egg odor can come from dissolved hydrogen sulfide gas or certain bacteria in the water, and CDC says hydrogen sulfide can be naturally present in well water.
Why does only my hot water smell?
EPA says a smell that only comes with hot water is likely from a part in your hot water heater. CDC also notes that hydrogen sulfide can form inside hot water heaters.
Does TCEQ test or regulate private wells in Texas?
No. TCEQ states that it does not regulate private drinking water wells, and that the owner is responsible for maintaining the well and testing the water.
How often should I test my well water?
EPA and CDC recommend testing at least once a year for total coliform bacteria, nitrates, total dissolved solids and pH. EPA also says to test right away if the water's odor, color or taste changes.
What does a gasoline smell in well water mean?
EPA says a gasoline or oil smell indicates fuel oil or gasoline likely seeping from a tank into the water supply. Test the well right away.
Related Water Problems
Sources
- CDC/ATSDR: Hydrogen Sulfide Public Health Statement
- USGS: Sulfate reduction and hydrogen sulfide in groundwater (WRIR 02-4045)
- EPA: Drinking Water From Household Wells
- EPA: Protect Your Home's Water
- EPA: Private Drinking Water Wells
- CDC: Guidelines for Testing Well Water
- TCEQ: Groundwater Contamination Notification
- Texas Water Development Board: Trinity Aquifer
- Texas Water Development Board: Woodbine Aquifer
Start With a Test of Your Well
Every well system starts with a test of your well water and a straight recommendation built on what it finds, with no pressure to buy.
What happens next
- 1We test your well waterThen give you a straight recommendation built on what it finds.
- 2We recommend a systemMatched to your well, with no pressure to buy.
- 3We install itClean, and we walk you through how it works.