Place the pineapple and mint in a water pitcher. Using a muddler or the back of a spoon, muddle the pineapple and the mint a bit. You want to break up the pineapple a bit and bruise the mint a bit.
Top with filtered water.
Refrigerate overnight or for 12 hours.
Strain pineapple and mint out. Store the infused water in the fridge and drink within 3 to 4 days.
Notes
Fruit - almost any fruit will work. Strawberries are especially nice. Cucumbers will also work. Almost any herb will work. You may need less of stronger herbs like rosemary.