Dear Sir;
When I fill up the washer in my basement I always notice a rotten egg smell, like sulfur. Any suggestions?

Do you have well water? Do you get this odor if you fill up a sink or bathtub?

I have city water and you can also smell this in the bathroom sink only, which is upstairs. You can't smell it anywhere else.

Sounds like a trap isn't either correctly installed or a drain might be leaking. And yes you can have a leak on the top of a drain that lets sewer gas in yet never leaks water. I've actually had that happen,

HI Janetave...

The washer and the sink, right?

I'm going to go with the idea that this might be an issue with the ANODE ROD in the water heater... maybe/maybe not?

Do you find the smell associated with hot water, warm water or cold water? If hot or warm water result in the smell then there is a good chance the anode rod in your water heater is reacting with your water and is causing a sulpherish odor/issue.

Let us know about the temp. of the water. Let us know about how old the water heater is (if present) and if you have a water softener in the home (and if the cold water entering the water heater is softened, too).

Back to you...

Mark