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. Wherever you are in Arizona, two questions narrow it down: does the smell come from the hot tap only, and is your water from a city utility or a private well? Below are the Arizona utilities I've checked by hand, each with what its own water quality report says.
More Arizona cities are being checked now. Not listed? The general rotten egg guide covers the same causes.
Your water heater's anode rod — a metal rod that keeps the tank from rusting — is reacting with bacteria inside the tank. That reaction is what makes the smell.
Many people flush the water heater and swap the anode rod for an aluminum or zinc one instead of magnesium — magnesium reacts more.
Groundwater sometimes naturally carries sulfur bacteria or a gas called hydrogen sulfide. It's usually just a mineral characteristic of the ground in your area, not necessarily a change in the water itself.
If the smell is new or sudden, many people get their well water tested. Otherwise, an aeration system or an "oxidizing" filter typically clears it up for good.
Bacteria living naturally in your household pipes are reacting inside your plumbing — this is a plumbing thing, not usually something in the water your utility sent you.
Running your taps for a few minutes clears this in most cases. If the smell hasn't gone after a few days, telling your water utility is the next step — they'll want to know.
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.