When it leaks, it really leaks....

My in-laws go on vacation and bad things happen. They have a rented out area that is an newer extension of the old house. The extension is on-slab construction with only one story. (There is the extension is built on a concrete slab that is on grade. There is only one floor and a roof over that one floor.)

Two leaks were found.
1) The hot water tank has a leak. I can get the tank replaced.
2) There is also on the hot water supply line next to the hot water tank. The hot water supply line feeds the bathroom and is grey plastic coloured and runs down into the slab. It seems to curve into the concrete and a pinhole crack has developed. There's a lot of sand in the area.

My plumber has looked at the plastic pipe and noticed the sand as well. His comment was that there was likely other cracks and it made more sense run new supply lines to the bathroom.

Initially he suggested running it through the ceiling, but I don't think he noticed that it was also the attic and an unheated space. Are you allowed to run supply lines through unheated attic spaces? I wasn't sure. (I'm in Vancouver, BC, which is quite temperate.)

An alternative is to open up lots of drywall and run it roughly at knee height and re-drywall. I'm not sure how to get the supply line across the a hallway....

The house wasn't built by my FIL, but I suspect some plumbing bits are done by him. I don't understand the two hot water supply lines shown in the picture. The left hot water supply (the leaky one) comes from a white plastic connection and goes under the slab to the bathroom. The right one connects via copper pipe.

I believe in doing this right, by the code with no code violations. I hope my FIL doesn't read this.... :-)
RWW