Indeed there is~
You just need to go to Map maker\\Objects and you will see the 'New Water' button. Just click that and you will see a square of water.
There isn't a way to re shape it, though if you can find an object similar to the shape you need, you can re-texture that object and use the water's textures and animation.
Not too sure how to do that but people have done it~
That shouldn't happen unless you have the default water material files that came with feralheart... Does it look white when you test the map?