If water gets into your sand supply hose, then you should turn off your pressure washer, disassemble the sandblasting kit.
Remove the sand wand from the sand (since you don’t want your dry sand to get wet). If your model comes with a gun trigger, hold it open, this may aid in removing water.
If you can, remove the hose from the rest of the kit and let it air dry.
You can continue working once the hose is dry, a trick I use is to have a few spare hoses hanging around.
A tip or rather a technique I use is to keep the sand bucket and sand wand elevated above my water wand, this way the water tends not to flow back down the sand inlet hose. If it does happen, it’s important to act quickly to salvage the situation; otherwise it can take a while before you can get back to it.