Run your hands down the hoses to make sure the hoses feel firm, not soft or pliable. If the hoses are soft to the touch, replace them to prevent failure.
Squeeze each hose at both ends and pay attention to how it feels. If you can feel ridges when you pinch the ends of the hose, that’s an indication it’s failing from the inside and needs to be replaced.
Check the ends of each hose to ensure it’s fully connected and not slowly slipping free.
Use a screwdriver to snug up the clamps at the end of each hose. Depending on the year of your VW Passat, you’ll need a Phillips or flathead screwdriver to do this. Make sure the clamp is snug but not too tight. If you tighten the clamps too much, you can cause a tear or rip in the surface of the hose.