The nastiest leaks aren't the ones that flood the kitchen at 3am. They're the ones that put a slow drip inside a wall or under the slab for six months and only announce themselves when the water bill triples or the flooring starts to warp.
Three quiet warning signs to watch for: (1) a warm spot on the floor where there shouldn't be one — that's usually a slab leak on the hot supply. (2) The hiss of running water when nothing is on. Stand in a quiet hallway at night and listen. (3) A patch of grass in the yard that stays green when the rest goes brown — that's usually the sewer.
The meter trick: shut every fixture off, note your meter reading, wait an hour, look again. If the little triangle spun even once, you have a leak somewhere. Then it's a matter of finding it. That's when you call us. We locate acoustically or thermally so we don't have to cut holes we don't need.