AquaTweaks Mod 1.7.10 is a small, clientside, coremod, which aims to improve the way fluids look around non-solid blocks. In its essence, it renders fake water into ladders, fences, signs and the likes, making them not look as derpy underwater.
Note that these changes are purely of graphical nature. Fluids will not actually flow through blocks, but simply render into them.
How to install AquaTweaks Mod 1.7.10
Download Links for AquaTweaks Mod 1.7.10
For Minecraft 1.7.10