Why does my water sometimes smell like sulfur?
The "sulfur" smell usually comes from the water heater. If a water heater is not used often (a home or business that is unoccupied), it does not empty and replenish itself frequently with fresh water.
Even when a water heater is used a lot, a new water heater can develop this smell after about 6 months, when the cathoid rod inside the unit starts disintegrating. The rod is the sacrificial anoid made of magnesium that dissolves inside the tank and the magnesium is what gives off the "sulfur" smell when it is dissolving. You can sometimes eliminate the odor by draining the water heater, then letting it refill.