Checked by Sunni Parks ·
A rotten-egg or sulfur smell is one of the most common water complaints there is, and it's almost always about where the water has been sitting, not something added to it.
Causes and what people typically do are based on published guidance from the EPA and state drinking-water programs, not guesses. The zip lookup pulls from EPA's public violation records (SDWIS) and a utility's own water quality report, hand-checked utility by utility rather than scraped.
This tool provides general information based on published EPA and utility data, and common causes reported by water quality professionals. It is not a substitute for laboratory water testing, a licensed plumber's assessment, or guidance from your water utility or local health department. WaterCheck does not guarantee the accuracy, completeness, or timeliness of the information provided and is not liable for decisions made based on it.
Mesa's own water report says a sulfur or rotten-egg odor usually isn't the water itself — it often means the water heater needs to be flushed, and a foul smell from one sink or tub can mean the drain's P-trap needs cleaning. The city's suggested test: run water from the outside hose spigot where water enters your home. If the smell isn't there, it's coming from inside the house.
Where Mesa's water comes from depends on where you live. The City Zone mostly gets Salt and Verde river water through the Salt River Project, treated at the Val Vista plant (about 40% of Mesa's water in 2025). The Eastern and Southern Zones mostly get Colorado River water through the Central Arizona Project (about 52%). The other ~8% came from 34 deep aquifer wells, usually blended with surface water — though at certain times of year some City Zone customers receive only well water.
The City of Mesa's 2025 Water Quality Report says most odors people suspect are in their water can be fixed with in-home maintenance — a sulfur or rotten-egg smell often means the water heater needs flushing. Compare against the outside hose spigot: if that water smells fine, the source is inside your home.
Partly. About 8% of Mesa's water in 2025 came from 34 deep aquifer wells, usually blended with river water. At certain times of year some City Zone customers receive only groundwater. The rest comes from the Salt and Verde rivers (about 40%) and the Colorado River (about 52%), depending on your zone.
Mesa's water quality team is at 480-644-6461 or water.quality@mesaaz.gov. If the smell is in both hot and cold water, from every tap including the outside spigot, it's worth letting them know.
Not on its own in most cases. The smell almost always traces back to bacteria reacting with either your water heater's anode rod (hot tap only) or naturally occurring sulfur bacteria in well water or household plumbing (both taps) — not something added to the water. It's typically a nuisance issue rather than a safety one.
That points to the anode rod — a metal rod inside your water heater that keeps the tank from rusting — reacting with bacteria in the tank. Swapping it for an aluminum or zinc rod instead of magnesium usually solves it, since magnesium reacts more.
Not necessarily. Groundwater often naturally carries sulfur bacteria or hydrogen sulfide gas, which is usually just a mineral characteristic of the ground in your area rather than a sign of contamination. If the smell is new or sudden, getting the well tested is still a reasonable step.
If it's coming from both hot and cold taps on a municipal supply, it's usually bacteria reacting inside your household pipes. Running the taps for a few minutes clears it in most cases; if it lingers for days, telling your utility is the next step.