There is no specific place to find a water stone, or any other item for thatmatter.Just Keep looking.Good luck
underground
Dig it out in the underground.
You can find it somewhere or you can go underground and dig it up.
Collect 15 Blue Shards underground and trade them.
in the underground tunnels.
You cannot get a waterstone from Diamond . You can trade one into your game card from a previous version of pokemon , or meet someone in the underground maze that has one . You can find a waterstone in the underground maze in Pearl . Though there is a 2% chance that a stone from Pearl can be found in Diamond .
You can find all the stones while digging in the underground, or you find them in the Solaceon (Unown) Ruins. There are several empty rooms in the ruins with single rocks in them. Use your item finder on your Poketech and you'll find a Thunderstone, Firestone, and a Waterstone. Hope this helps!
i fond mine underground while diging
sometimes found in the underground tunnels in the rocks
Exchange Blue Shard with the Waterstone. You'll find waterstone in Abandoned Ship, too.
you can get many waterstones underground you just go there by the exporer kit
You can buy it at the Cleadon department store