[cstreit]

A gallon of bleach in the well would be WAY too much.

The sulfur smell is usually caused by a bacteria that eats certain organics and emits the gas. Killing it will work for a few weeks maybe. It can also be caused by iron itself in the water.

I'd start with 1/2 cup bleach in the well and tank if you want immediate results. Be sure to flush out your lines after smelling it, bleach causes rapid oxidation of minerals and iron in the water that can ruin equipment inside. They actually make a sterilizer that is LIKE bleach made for RV tanks that might be better?

Then I'd call a well place and have them analyze the water. They'll tell you what is causing it and then you can decide on an attack plan if you want to deal with it.

My neighbor needed an iron filter to get his water clean. For us, it took a big carbon filter... Really depends on the cause...