I use different grades of water.
From "best" (most potable) to worst ...
- Distilled water, that I distilled myself, I know its good. Use this for drinking when sick with some kind of stomach ailment to make sure it isn't some of the lower grade water that is causing the problem.
- Bottled distilled water, for keeping water in the batteries.
- Bottled spring water, for drinking.
- Tap water, this is water I have in containers that I got from the tap somewhere that I believe to be clean, not filtered. I'd put water from other people's water makers in this category if they made it from ocean water. Good for cooking, drinking.
- Spring water, this is water that comes from a fresh water source such as a creek where I know it is clean because I know where it originates, would use in preparing food. Rain water is in this category. Filter this, good for cooking, drinking.
- Old water, this is high grade water that was stored for a long time in containers, or left in the sun, and may have a bit of a bland or plastic taste to it and might not be that good for you in large quantities. Tastes flat or tastes bad in some way but there is no reason to suspect it is dangerous.
- Boiled water, Fresh water (below) that has been filtered and boiled.
- Fresh water, this is water from a stream or other fresh water source that is fresh (not saline) but could be runoff from a cow field for all I know, talking basic river water here, or tap water in foreign countries with questionable treatment. Can be used in the pressure canner (outside the jars, not inside), but I wouldn't drink it or cook with it. Good for washing clothes, taking showers, etc. Less inclined to distill this, would rather distill "cleaner" water from the ocean.
- Salt water, water out of the ocean. Good for washing the boat, washing mud from the anchor, cleaning things but some things need a fresh water rinse. Prefer this water for any use that it is good for to save the fresh water for something else. Can be distilled.
I don't keep water in a single tank, I keep it in smaller containers. The only water I would filter is the water I called "spring water" or "fresh water" above. I can see why people with large tanks would also filter tap water, but I don't bother.
Water is like a fine wine, "Miami Lightly Chlorinated Tap 2008", "Walmart distilled 2012", or maybe "S/V Spirit's Watermaker 2011".