13 Plumbing Tricks of the Trade for Weekend Plumbers

The best way to disconnect a soldered pipe is to cut it. But sometimes you can't—either because you can't get a cutting tool into the space or because cutting would leave the pipe too short to make a new connection. The solution is to heat the joint and pull off the fitting as the solder melts.

Have a wet rag handy and immediately wipe away the molten solder before it hardens. (Wear gloves to prevent burning your fingers!) Sometimes a quick wipe will leave the pipe ready for a new fitting. More likely, you'll have to scour off some excess solder with sandpaper or emery cloth before you can slip on a new fitting.

Metal drain lines under sinks look a lot more reliable than plastic. But plastic is better in almost every way. It's cheaper, easier to install, and easier to adjust or tighten if a leak develops. And unlike metal, plastic won't corrode. So when a metal drain leaks, often the smartest move is to replace the entire assembly with plastic.

Shutoff valves under sinks and toilets have a rotten reliability record. Sometimes they won't close completely; sometimes they won't close at all. In either case, there's an alternative to replacing the shutoff. Most home centers carry “piggyback” shutoff valves that connect to existing shutoffs. Just disconnect the supply line and install the new valve (a new supply line is a good idea, too). If the old shutoff closes most of the way, you won't even have to turn off the main water valve; just set a container under the valve to catch the trickle while you work.

Before you run a drain snake into a clogged pipe or disassemble the trap, there are a few other tricks worth trying: Often, you can yank out a clog with a flexible-shaft pick-up tool (shown above) or a Zip-It (below). Likewise, a wet/dry vacuum just might suck out the clog.

It's tempting to crank supply lines on tight, just to be safe. But overtightening supply lines is actually riskier than undertightening. A loose connection that leaks is easy to tighten, but overtightening can wreck rubber seals and crack the threaded nuts. So get into this habit: Make the connections at both ends of the supply line finger-tight, then give them another one-eighth to one-quarter turn with pliers. If they leak, snug them up a little more.

When you're replacing a toilet or a faucet, you can save a few bucks by reusing the old flexible supply lines. But don't. Plastic degrades over time, and even a small leak can lead to catastrophic water damage. It's a small risk, but not one worth taking. Buy new lines that are encased in braided stainless steel; they're much less likely to burst. But even if you already have braided lines that are several years old, replace them.

Tape and dope are equally reliable for sealing pipe threads. The main advantage of tape is that it won't smear onto your hands or tools and end up on the carpet. Here are some tips for tape:

• Cheap tape works fine, but the thicker stuff (often pink for water, yellow for gas) is easier to handle and tears more neatly.
• Unlike dope, tape is for pipe threads only. Don't use it on compression or other connections.
• How many times should you wrap around the pipe? There are no rules, but the most common answer we got from pro plumbers was three.
• Always wrap the tape clockwise around the threads. Otherwise, the tape will unwrap as you screw the joint together.

Corrosion and mineral deposits have an amazing power to lock parts together, making them almost impossible to disconnect. Often, the best solution is to cut the stubborn part. Either slice it off or cut kerfs in the part so you can break it off. A hacksaw blade works well. Oscillating or rotary tools work even better.