Is your question "how to keep water out of the snorkel"? or washing in general especially regarding the engine?
Some snorkels and air intakes can have a water drain on the bottom to deal with small amounts of water. If not, you couldn't drive in the rain. I pressure wash my vehicles including the engine. Things I don't directly spray are connectors and on my Land Cruiser, the distributor. Im not saying I don't get them wet and I do spray them, I just don't focus on them. If I point the spray directly at a door seam, some water will be forced inside. Later model vehicles (mid 90's and up) are pretty water resistant.
Hope this helps.
Scott