About 3 years ago I moved some of the radiators in my house. In order to do this I cut the existing copper pipes & ran new pipes to the new locations using mdpe pipe and push-fit fittings (making sure all the copper remained correctly earthed, of course). This has all worked perfectly since then (and I mean perfectly -- I had a new combi boiler installed in April, and hadn't had to repressurize the system between then and a few days ago), but suddenly the day before yesterday I seem to have developed a fairly serious leak in one of the pipes I worked on. Does anyone have any idea what might have caused this, or what I can do to make sure this doesn't happen again in future?