once in Maine and once in Virginia. I used the Hookah compressor, but a dinghy pump might work, if electric. A wet/dry shop vac sucking might be better still - centrifugal pumps due better creating vacuum than pressure. You way want to pay particular attention to any complicated or odd water fittings: I disassembled the tempering valve on the domestic water heater because in Maine it got ruined by freezing, no way to effectively blow it out.

While ethanol is commonly used, I wonder about it: many plastics are sensitive to its effects, and if pooled in an otherwise air filled space it seems like the ethanol might evaporate over some time.