Primal Water is made from motes of water and can be commonly found as a drop from Water Elementals. There are several low-mid level 60 farming areas. In Zangarmarsh there at least 5 mobs that have anywhere from a 7-15% chance to drop motes of water. Those 5 mobs are Bloodscale Sentry/ Darkcrest Sentry, Bloodscale Elemental, Bloodthirsty Marshfang, and Lagoon Eel. In addition to farming motes of water in Zangarmarsh as a low to mid level 60 you will also be able to farm Lake Spirits, Muck Spawn, and Lake Surger's in Nagrand with a 13-15% drop rate. These are located in the water near Halaa, the lake near Throne of the Elements, and the lake near Sunspring Post.
Motes of Water also drop in instances of The Steamvault and Black temple off water elementals.
For those of you that are ready for some serious high level mote of water farming get out your flying mount and head to Terrokar Forest or head into Shadowmoon Valley at the places shown on the map.