Take a look at the replies to my post today asking about Fernox leak sealer.
Expert opinion is varied but some have had good success in sealing up inaccessible pinhole leaks. Might be worth £20 to try it out before digging up the floor.
Expert opinion is varied but some have had good success in sealing up inaccessible pinhole leaks. Might be worth £20 to try it out before digging up the floor.