The pvc pipe shown is a condensation pipe from a high efficiency gas furnace  located inside the garage. The furnace is a high efficiency furnace and therefore does not need metal exhaust flu but uses 3 or 4 inch PVC or ABS (white or black plastic) pipe to exhaust fumes from burning gas. It is at a much lower temperature and thus can create quite a bit of condensation. The condensate pipe from a high efficiency gas furnace usually exits outside the home. The issue with the one pictured is the water(condensation), as much as several gallons a day, is being directed back towards the foundation. This can cause problems by pushing water back into a crawl space or under a foundation. A simple solution is usually put a splash guard under pipe directing water away from foundation. This one had a unique solution from the home builder, second picture shows solution. Visit our website at Clear View Home Inspections

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