I only use distilled, spring, drinking (whatever is cheapest that day) in my iron. Our tap water here is aweful, we have to unscrew the water saver screen on the kitchen faucet every night and empty that days rust collection from it, the tap water kills my houseplants, ruins our clothes if I don't put white vinegar (1 cup per load) in the washer with the detergent, and I ruined 2 irons before I figured out why. Dollar General has gallons of water for 75 cents. In the long run its cheaper than buying new irons every couple of months. We buy water for our own consumption, so I figure another couple of bucks a month for the iron and houseplants won't make me or break me.