Spilled water on MacBook air

You should take the laptop to Apple or an Apple Authorized Service Provider to be examined and repaired.

FYI, it really isn't good to tilt or turn an Apple laptop upside down after a liquid spill. It just causes any liquid to have a better chance of reaching the electronics. There is actually a mylar cover beneath the keyboard which does a fairly good job of keeping light liquid spills on the keyboard from getting inside to the Logic Board.

The best thing to do is to power off the laptop and unplug it. If the laptop has a removable battery (one which doesn't require opening the laptop), then try removing the battery without tilting the laptop. Let the liquid evaporate which can take a while depending on the type of liquid. I also don't advise using rice as the rice will get inside the vents and clog things up.

Once the liquid drys up, you can try an SMC reset if the laptop doesn't power on.

The initial liquid damage is not the only concern. The laptop may work fine for a while after the initial liquid drys up, however, after several days or weeks corrosion will occur on the electronics which can cause a failure.

Be prepared for an expensive repair.