I have a strong sulfur smell in my cold water. I live in the Orlando area, am on city water, had my whole house re-plumbed to pex pipe several years ago. I have a water softener that I turned off thinking it was the cause. I have drained my water heater and flushed the lines in the whole house several times. This helps for a week or so but the smell comes back. I have checked with several neighbors and no one has experienced this problem. Any ideas of what is wrong and how to fix it?

Julieb, you turned off the water softener, did you put it on by-pass?

Did you flush your water heater or just drain it? (should flush)

Are you finding debris in your faucet aerators?

Make sure softener is bypassed when checking cold water for smell. If you have a sediment pre-filter, bypass the softener, remove sediment filter, fill housing with 5% household bleach, run water at furthest cold water faucet until bleach smell, shut off, open all cold water faucets until you smell bleach. Let this sit for several hours, then flush all lines of bleach until clear. DO NOT use any water during this time. Also the anode rod in water heater may be eroding. This will cause a sulfur type smell. Do not drain water heater. Flush from bottom of tank (with water on) and run for several minutes to floor drain. If anode rod is dissolving this will flush some of the debris out. You may need to do this several times. If smell is coming from softener you can add a small amount of bleach to salt tank to sanitize system. DO NOT add bleach to salt tank if you use salts with any additives IE: Red Out, System Saver, etc.
RJ

Julie, Most water supplies have sulfates present in the water. If bacteria is introduced into the plumbing system it can attack the sulfates and sulfate reducing bacteria can occur. This will give a strong sulfur /rotten egg smell. The water softener/plumbing system are the perfect place for this to occur and can be more prevalent in water heater. Bacteria can be introduced into plumbing system by simply handling your kitchen faucet and many other means. Chlorinating the home will quite frequently alleviate this problem.
I hope this helps,
RJ