First, verify whether you have a leak by checking your water meter. Or if you have a well at your home, listen for the sound of the pump kicking on when water is not in use. If it does, you have a leak. Once you have ascertained this, rule out toilet leaks or faucet drips as the source of the problem.

Contacting a professional is probably the homeowner's best course for underground leak detection. Most leak detection methods for underground pipes involve sonic leak-detection equipment that identifies the sound of water escaping a pipe. Small leaks, especially those under high pressure, are (ironically) easier to detect than large ones, because they are noisier and easier to hear using hydrophones. In general, the louder the noise, the closer one is to the leak. Factors that affect the sounds generated by a leak include water pressure within the pipe; the pipe material and diameter; soil type and soil compaction; depth of soil over the pipe; and the surface cover.

Once found, repair clamps, or collars, can be used to repair small leaks. Larger leaks often require the replacement of one or more sections of pipe. It may be more economical to completely replace plumbing in older pipes, especially if they have a history of leaking. Copper pipe, considered the industry standard, is not immune to this problem, but can be affected by corrosive soil, acidic water, aggressive flux, or sloppy installation.