sure can, only you need to concern yourself with freezing if they are exposed to cold or wind. If that is the case, they can be insulated and if need be heated as well. What type of project are you considering that needs this water source?
I bought an older home that was foreclosed and neglected. The kitchen and back bedroom havedrop ceilings, I am in the process of removing this to be able to put in a drywall ceiling. This part of the house was the addition. I ran into the small piped there. The house itself has a very small to non existent crawlspace under entire house as well as the addition part. I think the reason you mentioned of poss. freezinmg is why they were run thru the ceiling in the first place. I am not looking to borrow trouble by attempting to have them repiped under house. Our county coude (AA) does not iseem to indicate that this is neccessary.