We have well water and notice that the water (or the wash--usually the wash) *smells* based on certain times of the year and/or due to rain/how much rain we've had (due to the fact that the earth strata gets changed/sifted through by the rain water).
Other than leaving the washing machine open so that smells don't stay inside when it's empty, we don't do much. There's not much that can be done when it's the environment doing the changing (we notice the same thing with soap, how sometimes the dishsoap will leave lots and lots of soap bubbles in the sink and other times, you can barely tell that any soap has been put into the water).
The only thing we did four years ago was we put in a reverse osmosis system on our drinking water faucet, mostly because we live in an area where there is still some farming and didn't want any pesticide residue getting into our drinking/cooking water. Also our nitrites are a little higher than we'd like, so ee put in the R/O system. Wonderful drinking water and clear ice cubes--can't be beat!
We also have a filtration system for the water coming into the house before it goes into our tank. Where we live it's quite sandy, and that helps capture some of the grit.