7 Answers

A sewer, or "rotten egg" odor, from your tap water could be the 
result of several problems in your own home, and may not be 
directly related to the water supply. If you detect the odor in your 
kitchen faucet, it could be the result of a partially clogged drain or a 
dirty garbage disposal. The easiest way to verify this is to check 
another faucet in the house. If the water from the other faucet smells 
fine, then, more than likely, the bad odor is a result of a dirty    
garbage disposal or remains in your sink’s trap. 

A hot water heater can produce a rotten egg odor when it is turned on. 

 To determine if the odor is from the hot water heater, 

go the a sink closest to the water heater and fill a glass with water

 from the hot water faucet and a second glass from the

 cold water faucet and smell them.  If the offending odor is detected only from the glass of water taken from the 
hot water faucet, the problem is most likely originating from the

 water heater.  Newer water heaters are a real problem. 

 This also works to increase the smells.  Flushing the water heater 

yourself, or contacting a 

plumber to perform the flushing, and then resetting the water heater to the correct  

temperature will, in most cases, solve the problem

well water does not smell great either

If you are using a well sometimes there are natural sulfides in the water table where you live.The rotten egg smell is sulafer in lay men terms harmless just a nuisance!

Hydrogen sulfide gas can occur in wells anywhere, and gives the water a characteristic “rotten egg” taste or odor.

Move to Hawaii.  We have the best tasting water in the nation!

Where is your water coming from, this makes a difference. My well water use to be that way mainly if set around, like overnight.

We had it checked and it was high in sulfides, harmless but never the less a pain.

Here you go:

http://www.mrwa.com/watersmellrotteneggs.htm

I lived in Hanford, CA for awhile. It stunk sooooo bad. The place was full of cows and their farts and the water stunk of Sulpher.  We actually moved out of that town because of the odor.