There are two things to consider here.
The first is particulates in the water. A good in-line filter will do the job well. There are some cheap ones you can just attach to a hose attached to a faucet or more elaborate models that can be plumbed in.
The other thing is dissolved minerals that cannot be filtered out. Sometimes an activated carbon filter will help here. A water-softener for hard water is common as well, but introduces salts into the water that will leave marks on film and paper, so a distilled water final rinse is usually needed. If the water has lots of dissolved minerals that cannot be removed, you may have to use distilled water for some or all of your chemistry and certainly for a final rinse. If you really want totally clean water in the darkroom and have lots of dissolved minerals in your incoming water, then a reverse-osmosis unit might be worth looking into.
It all depends on what is in your water. Your local water utility will have test results, so contact them to find out. If you're on a well, you will have to take samples to a testing facility.
That said, if your water is just "hard," i.e., has lots of dissolved calcium carbonate, then you can likely use it for washing and for mixing working-strength chemicals (used distilled for concentrated stock solutions). The developer will be the most critical here. If your water is very hard it can slightly increase the activity of the developer. As long as you are consistent, however, a 5-10% increase shouldn't make a significant difference.
Best,
Doremus