You can grow the roots in water, as long as the leaves remain above the water.
I have several pots of it, where the roots are simply submerged in water. There's no soil in the pot at all. They've been growing like this for years.
I've also grown it in my three tanks, without problem. I put the bottoms with the roots into the water, and let the tops with the leaves hang out above the tank. The plants did really well in the tanks, and my fish liked swimming around the roots.
Just make sure the leaves are above the water, and you should be fine.