Water has always been troublesome in HatPC. The Water Tap, Water Tap Crates and Water Crates gave you some options, but all in all these have always been too restricting. I can't remember all the cool ideas I have had that either required terrible work-arounds or simply didn't work at all. Seeing how Aeon will hopefully fix anything HatPC did wrong, I'll give a few suggestions to extend this.

-Global Water Level. The Global Water Level acts exactly the same as the Water Level in HatPC. Every non-solid tile up to that height will get filled with water, regardless of any walls blocking off sections of the map.
-Local Water Level. As opposed to the Global Water Level, the Local Water Level will only create water in its "room". It won't allow any water to pass through walls or other objects like it, essentially acting like a Water Tap that has filled up to that point before the level starts.
-Water Taps. As opposed to Water Taps permanently filling up the level with water in HatPC, I think it would be better if Water Taps would only fill the level up till their level. You can still get the same effect as in HatPC by simply putting the Water Tap at the highest possible level, so you lose very little by doing it like this.
-Water Drains. I don't think I need to explain this. Exactly like Water Taps, except it lowers the water level instead of increasing it.
-Water Tap/Drain Crates. I think it would be better if Water Tap/Drain Crates didn't work like switches for existing Taps/Drains, but instead created a new Tap/Drain at the location of the crate. You could still imitate a low crate activating a high tap by triggering the crate with a arrow or something, though making it work like this will still make you lose a few options. An alternative is linking each crate to a different Water Tap/Drain, though I think this could overcomplicate the level editor.
-Water Stop Crate. A crate that simply stops all active Water Taps and Drains. New Taps and Drains can be activated again through crates after triggering the Water Stop Crate.
-Water Gates. An entirely new suggestion. Water Gates would act like an activatable Local Water Level. If you trigger a Water Gate, water comes pouring out/in the local water level will almost instantly be raised/lowered up that point.

These are really good ideas, and I feel they can all work and be a massive improvement over HATPC's water, (not hard, lol) and would make water a much more usable item. I especially like the global/local water levels idea. Good work!

Rather than just "Stop Crates", I was thinking something along the lines of On and Off switches for both taps and drains?

I like csd's psot too, that's what I had in mind while reading everything. the ideas are not new to us I think, only to hatpc.

Not sure if this is directly related, but are we still implementing the "air bubble crates"?