Welcome to the wonderful world of Gypsum....yup, you drilled into sheetrock !!!! /forums/images/graemlins/grin.gif
Most likely the sulfur is from the well water perculating through gypsum. The water picks up sulphur compounds that disolve. Look here for info on
Gypsum.
The bad news is that the stank is stinky. The good news is that its not really bad for you ( if you can drink it without gagging /forums/images/graemlins/grin.gif )
"Sulphate (SO4): Sulphur, the "S-part" of sulphate, is essential in maintaining healthy hair, skin and nails. It also aids the liver in bile secretion.
Deficiency of Sulphate: Lack of sulphur inhibits the body to repair damaged cells properly. "
The use of an aerator is great as the sulpher compounds readily oxidize ( when combined with air ). The prove this, draw a small glass of water and let it sit on the counter for a few minutes. Now draw another fresh glass and compare sulphur stank. I'll bet you'll notice the difference.
You may also find that the levels of sulpher will vary by use and may even diminish.
Check out your PH and other mineral content at a water test shop. I'll bet you have pretty 'rich' water and may need additional treatment.