Replacing a P-trap is a small job that may seem more complicated when you have to mix plumbing materials to get the job done. The part of the drain assembly that extends below the sink is called the tailpiece, and it's usually made of metal. P-traps can be plastic or metal. The plastic ones are corrosion resistant and easier to install, so are more commonly used. It isn't an issue if the two components are made of dissimilar materials, because the flange that seals the trap opening is always plastic. So don't be intimidated. Put your DIY skills to work and you can save yourself the cost of a San Francisco service call.
Compare the relative diameters of the P-trap and tailpiece by removing the nut and flange from the trap opening and sliding the trap up the tailpiece. If it just fits, they are the same diameter, but if there's a large gap, the diameter of the tailpiece is probably 1 1/4 inches while that of the trap is 1 1/2 inches. If the latter is the case, use the thicker of the two flanges that came with the P-trap assembly to make the connection.
Slide the nut up along the tailpiece with the threads facing down, then fit the flange around the end of the tailpiece and slide it up.
Insert the end of the tailpiece into the trap opening and slide the trap up until the opening is slightly higher than the drain opening in the wall. If the opening isn't higher than the drain, the trap may leak, no matter how much you tighten it.
Slide the flange down the tailpiece and fit it into the trap opening, then slide the nut down and screw it to the trap. Tighten the nut as much as you can by hand.
Screw the other end of the trap to the drain line, which should have a threaded adapter glued to it for this purpose. Tighten the connection by hand, then tighten the swivel nut in the middle of the trap by hand.
Fill the sink, then open the stopper and allow the water to drain. Inspect your connections. If any of them leak, tighten them further. You may need to use a pipe wrench or adjustable pliers if you can't tighten them sufficiently by hand.
Things You Will Need
- Pipe wrench or adjustable pliers
- A P-trap flange seals water by compression. Wrapping plumbing tape around the threads of the trap opening before screwing on the nut won't improve the seal.
- Don't consider the job done until you are sure there are no leaks from the trap. Even a small leak can damage the base of the cabinet or the floor and promote the growth of mold.
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