Why is {something} broken?

Because this is my first mod ever and I'm sloppy. Post to the discussion and I'll try to fix it. Alternatively, if you don't like how something works, unzip the mod and change it. That's what I did.

Where did my item go?

Did you try to place waterfill on an isolated tile without any other water nearby? Then your item evaporated. The real whole purpose of my completely stealing and rewriting the Waterfill mod by untraceablesmurf was to prevent you from doing that like Cox's CanalBuilder mod did (does?) even though that mod hasn't been updated for 1.1 and isn't supported anymore.

Why is it so expensive?

If you want to spam water all over your map and use it to build moats around biters and drown your enemies, this isn't the mod for you. It's supposed to be expensive, inconvenient, and annoying to do more than add a few tiles of water near where there was water already to make your builds look pretty. If you want to pipe water into an assembly machine for a stack of 200 waterfill items in less than five minutes that you can place anywhere you want for the low investment of a few green science packs, get Waterfill from untraceablesmurf. I stole most of my code from that mod anyway.

Why is it still so cheap?

Wow, ok, not an invalid question considering that you could still pretty quickly and easily create an island for yourself with no biters if that's how you wanted to spend a few hours of gameplay. Post what you think would be an appropriate cost and I'll look into making a setting that makes waterfill even less practical. I don't know what I'm doing yet though so "settings" are a little outside my wheelhouse at this point. Also see question #1 and do it your own self.

I want my item back!

Admittedly I came up with the "evaporation" excuse because I couldn't figure out yet how to interrupt the tile placement so you didn't technically already place your item as a tile and then I programmatically removed it anyway. I think I know how I can do that and make the evaporation thing a setting. Future version, or question #1.