We have to replace some underground conduit. 1" pvc coated grc. To fuel dispensers. Veeder Root level sensors. They have been having trouble with these since they installed them. They have decided that the conduit is sucking in water from some where. Then they theorize that the water freezes and pulls apart, breaking the wire in the process. Today he said he wants this new conduit to never have water in it again, thereby stopping this problem. I looked at the original installation, where I could. It looks proper. All the joints that I could see had the coated coupling. Someone used a blue thread sealer at each joint. Is there any way to prevent ground water from entering at the couplings? I haven't seen any product that targets this problem. Some sort of tape?