Fresh water tank stinks

Sulphur smell is iron bacteria and hydrogen sulfide. I have a well at home and have this issue when we're gone camping for some time. It eventually flushes itself with water usage.
As suggested, you bleach the system (lots of articles will give you ratios of bleach, but you should not need more than a pint in an rv). You have to turn on your water at all faucets and make sure you have bleached water coming through them all --- hot, cold, shower, outside shower. Then, let it all sit for a good 24 hours before rinsing out.
This is all standard technique for 'shock chlorination' of water systems. No different in an RV. As mentioned, if the water going in is 'bad', of course, bleaching your system will have no effect.

Note: Use unscented bleach and be sure it is newer bleach. Bleach that has been sitting, after opened, for some time looses efficacy.

And yes, hoses can give you smells too, but not that sulphur odor.

2oldman wrote:
How's the hose you used to fill it?

... and is the hose rated for drinking water.

Generic water hoses, especially rubber hoses, contain chemicals that will give the water a foul taste.

2oldman wrote:
How's the hose you used to fill it?

2oldman has a good point. I always bleach the hose before using the hose to bleach the tank.

Moved from Forum Technical Support

How's the hose you used to fill it?

The hot water tank was drained and the water with bleach was pumped in to it and all though the spigots ,so it went though all the system, then it set for 24 hours then drained and refilled with a hose from the house.

Did you flush it through the whole system, including hotwater? Hotwater tanks are notorious for causing that sulfur smell.

Anyways...Its probably the water itself and not your system. Theres a safe bleach/water ratio to use for potable water...may consider going that route.