Plumbing problems arrive in all shapes, sizes and degrees of difficulty. Fortunately, plumbing techniques have evolved over the years, and to add difficulty to some plumbing problems, older houses have antiquated methods of plumbing systems that need maintaining and repairs, and eventually replacement.

Although galvanized-iron piping hasn't been widely used since the 1940s, it still exists in millions of homes. The problem with iron pipe is that it corrodes from the inside out, making it difficult to tell what condition it's in. The first sign of trouble often appears as a pinhole leak. If you don't patch the hole, it will grow larger without your being aware of it.

copper water-supply lines. The pipes and fittings are "sweated" together with solder, which is melted with a gas torch. Besides the obvious dangers of working with an open flame, it takes experience to make the hot solder spread uniformly so the sweated joint doesn't leak. And any moisture in the pipe will prevent a watertight seal.

Repair couplings work great on straight pipe sections, but they can't fix a leaky elbow fitting.