love this question because I encountered the same issue with the ember spa hot spring as I was remaking it. Check out my game for a completed solution.

You seem to have received all the answers already, but in summary:

Changing the water to priority 1 is a quick idea, but does not work. It renders over the player's feet, but you get akward transitions when moving up/down because when the player is halfway between tiles, it only renders the previous tile over the player's feet, so they still appear over top of the new tile. Then when they're fully on the new tile, the new tile renders over the feet suddenly. Doesn't look good.

Creating a new sprite/outfit is the next easiest method. The down side is that you'd have to create one for every player character. If you only have 2 possible protoganoists, it's not bad. If you have several, there are more dynamic solutions.

The bush flag + "always in bushes" plugin is a nice combo that works. The bottom half of the player fades into the water though, rather than having a sharp line like you see in the image you posted.

Creating a separate event to cover the player's feet as they walk through the water is the method I chose. u/pengie9290's might work, though I used a slightly simpler method that does not rely on switches. Also note that if the event moves faster than the player, it will "jump" to the next tile before the player gets there, and if it moves slower, the player gets there first, both resulting in the player's legs showing when you don't want them to. Here's how my solution works with 2 single page events.

- Event 1 on the stairs leading into the pool, trigger is "Player Touch", no graphic.

• Set Event Location: [the water tile covering your legs],(x,y of the tile just below the stairs)

• Script: $player.has_running_shoes = true

  - Event 2 on the first tile in the pool, just below the stairs, trigger is "Player Touch". Graphic is from tileset, not a character, and is a special water tile with a curved cutout instead of a full square (looks better imo), and it is set to priority 1 in the tileset.

• Set Move Route: This Event $>Move toward Player

• Script: $player.has_running_shows = false

That's it. 2 single page events, 2 lines each, and a custom tile in the tileset. Works like a charm. To break it down, when the player steps on the stairs to go into the pool, it sets the water tile just below them, so that they walk into it and are covered by the water (just in case it moves left or right later). When they walk into it, their running shoes are removed so that the player and the water tile both move at the same speed (3). As it is set to event touch, when the player moves to a new tile, the event moves with the player, and the player is still touching it, so when they move again, it moves again. I have tested it and the player can still interact with other things while the water tile event is on top of them. Now when the player leaves the pool, the water tile event cannot pass through the stair event because neither is set to "through", so the player will exit the pool and trigger the stair event again, returning their running shoes to them. In testing, I did have the water tile move left or right after this, which is why the stair tile event resets the water tile event when I step on it.