I guess the explanation of why is beyond me... but it seems that saying all you need for instant water, is the water.
Think of it this way: you could transmit a message using the entangled particles, but it would essentially be “encrypted”, and you can’t transmit the key to decrypt it through the particles. You can only transmit the key to decode the message through traditional, slower than light methods. So, at the end of the day, you might as well just use the slower method for the whole message and save yourself some trouble.