I found this installation the hard way while installing Hardie Board on the 1st floor matser bath. This is a cantilever section below double vanity from the master bath with all four supply lines attached directly to the underside of the subfloor. I got lucky and missed the pipe twice but hit it the third time. BTW 3 years ago I had to replumb the valve and supply line for ice maker from hot to cold in the house across the street.
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