Smartthings Water Sensor > Echo Dot

You can do it by creating a virtual door sensor, having the water sensor alert trigger the virtual door sensor, and having echo react to the virtual door sensor. It’s sort of a long way around to get there, and it does get glitchy sometimes where it doesn’t work for a few days, which isn’t great for a security feature, but it’s something you could try. This will work with any sensor which can be used as a trigger by smartthings.

Here’s the community FAQ for that:

FAQ: Can I trigger an Echo Action without Speaking to It?