This is a question faced by many that have or experienced a hidden underground water pipe leak. A full replacement can indeed remedy any hidden leak however is this solution really necessary? There is a lot of very good pipe buried out there and to best answer this question is to first understand the good qualities of the pipe you already have. Here is a link to my Pipe Facts
page which you may find helpful with your research. Since even good pipe can spring a leak, professional leak detection and repair is all too often the best and most economic remedy.