The techniques for replacement are easier to understand if you know how a drain trap operates.
The water seals the drain opening and prevents gases from rising up from the sewer system into your house.
Such objects often remain in the trap rather than getting washed into the main drain.
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Kits may come with additional adapters and parts that you may not need.
The various drain trap parts can also be purchased individually.
The trap bend and trap arm are secured with short, large-diameter nuts called slip nuts.
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Inside each joint, a vinyl slip washer seals against the pipe.
you could loosen the nuts by hand or with tongue-and-groove pliers.
Replacement drain traps are sold as kits at home improvement centers, hardware stores, and online retailers.
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Several sizes (pipe diameters) are available, including 1 1/4-inch, 1 1/2-inch, and 2-inch.
Bathroom sinks usually use 1 1/2"-inch traps, while kitchen sinks usually use 2"-inch traps.
Washers are provided that allow you to connect to the 1 1/4" tailpiece from a sink.
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2-inch traps are commonly used on shower and tub drains.
Check your drain fitting and branch drain opening to determine what size of drain trap you will need.
Tip
Some drain trap kits use a flexible, accordion-like trap arm or tailpiece extension.
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Most plumbers avoid this punch in of drain trap, and local codes may even outlaw them.
Smooth-walled pipes are a better choice.
If your configuration includes an extension pipe leading from the sink tailpiece to the trap bend, remove it.
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If the trap arm is stuck, twist it back and forth while pulling.
The sink tailpiece or extension may also need to be cut to length.
Add another nut onto the straight end of the arm, with the threads facing the straight end.
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Add a slip joint washer over this straight end, so the beveled end of the washer faces outward.
Fit a slip nut and washer onto the end of the sink tailpiece with the washer bevel pointing down.
Assemble the Parts
Slide the trap arm into the drain opening in the wall.
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Fit the trap bend over the end of the trap arm and onto the sink tailpiece.
(If a tailpiece extension is used, position it at this time.)
Slide the slip nuts against the fittings, and loosely thread them onto the threaded hubs.
A 1/4-inch-per-foot downward slope is the recommended pitch.
Hand-tighten the slip nuts.
If any joint leaks, tighten the slip nut gently with pliers until the leaking stops.
Be careful not to over-tighten the nuts, especially if they are plastic.
3280.606 Traps and cleanouts.Cornell Law School Legal Information Institute.
