The only mod with an (optional, user installation required) finite water tweak that I know of is GregTech... and that's not even in the DW20 pack.
Try starting a new world and see if it persists?
I`ve disabled Optifine and the water works again but I`ve lost some other textures.
One request I`d like to put forward is having FTB launcher display the version of Forge being used. My other core/jar mods show version numbers, Forge just says "MinecraftForge". Certain mods are compatible only with certain versions of Forge.