Smell from water system pump

[Johnny Slalom]

I have a 99 270. I just noticed a bad smell when I engaged the water system pump in order to use the head. This is the first time this has happened. We're very careful to use the head for number one only, pump out regularly and use disinfectant. It doesn't make sense to me that the pump would cause this smell. Isn't it only pumping fresh water to the head? I know there's a filter and that probably needs attention. Any other ideas? Advice would be appreciated.

 

[Carpediem44DB]

Does water at a faucet smell or is it only at the toilet that you smell the odor? You may need to clean out the fresh water tank and use a fresh water treatment like Sweet Water. Use the Zaal No Flex digester in your head system. Several threads here about its use and effectiveness.
CD

 

[Johnny Slalom]

Doesn't seem to be at the faucet or head. I'll keep checking. Thanks for the info on products-will check them out.