Clean up anything that was touched by water with 91% isopropanol and allow it to dry completely. No, do not use a hair dryer. The battery is sealed and will be fine unless the water results in connector corrosion. If the system was powered on when this happened, and suddenly cut off, the damage is already done, but if not, a thorough clean up (not just allowing the water to dry, leaving deposits behind) may save it.  
I accidentally spill about 0.2 liter of water onto the keyboard of my Alienware 15 r3, I turned it off, unplugged in less than 30 seconds and about 15 minutes later unplugged battery from motherboard. Now i kept the laptop upside down with back lid open and I also put dry fabrics below to absorb any water leaked. How long should I wait to restart the laptop? Should I use a hair dryer? Is there anything else I can do to prevent further damage to components? I am afraid that although unpowered, the water may still enter the battery and react with it, or it may enter into circuits, capacitors and sensitive parts and cause corrosion.  thanks in advance for any advice! 
15 R3, 0.2 liter of water spilled onto keyboard