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.
Since nearly all of Phoenix's supply is treated river water carrying a chlorine residual — not untreated well water — a rotten-egg smell in a Phoenix home most often starts inside the house: the water heater if it's the hot tap only, or a drain if it's one sink. A quick way to tell: run the cold outside hose spigot where water enters your home. If that water doesn't smell, the source is somewhere in your plumbing.
About 97–99% of Phoenix's tap water in 2025 was treated surface water from the Salt, Verde and Colorado rivers — Salt and Verde water arrives through the Salt River Project canals, Colorado River water through the Central Arizona Project aqueduct. The remaining ~2% came from about 20 city-operated groundwater wells. Every source is disinfected with chlorine before it reaches your tap.
Usually not. About 97–99% of Phoenix's water is treated river water from the Salt, Verde and Colorado rivers, disinfected with chlorine. Rotten-egg smells in Phoenix homes most often come from the water heater (hot tap only) or a drain trap (one sink only). Running the outside hose spigot is an easy check — if that water smells fine, the source is in your home's plumbing.
Only a small share. In 2025, about 2% came from roughly 20 city groundwater wells; the rest was surface water from the Salt, Verde and Colorado rivers, according to the city's 2025 Water Quality Report.
The City of Phoenix Water Services Department takes water quality questions at 602-262-6251 (weekdays, 8 a.m.–5 p.m.) or WSDCompliance@phoenix.gov. If the smell is in both hot and cold water, from every tap, and doesn't clear after running the water, that's worth reporting.
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.