Converting a garage into a salon, and I need to run water to the garage.there is a bathroom above the area I want to place the sink

If there is a bathroom above than it should be relatively easy to bring in hot and cold water. Just tap into h/c water pipes above and bring pipes down to garage. You can use PEX materials and SharkBite fittings and to finish the job a no time.

Now, what are you going to do about new sink drain and vent ?

Back to you... Milo