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Replacing Kitchen Pipes
2. Reseal a leaky strainer
The primary seal around a basket strainer is plumber’s putty, which doesn’t last forever. Over the years it can harden, shrink or crack. Sometimes you can stop a leak by tightening the locknut. But in many cases, the only cure is a new dose of putty. You can reuse the old strainer if all the parts are in good shape, but it usually makes sense to replace it. Expect to spend at least $10—cheaper strainers are less reliable. Since you have to take apart most of the drain assembly to get at a leaking strainer, consider replacing the drain lines if they’re old.
Basket Strainer Assembly
The hardest part of this job is unscrewing the old locknut, which is often welded in place by mineral deposits or corrosion. A special wrench designed just for locknuts, called a “spud wrench” or “locknut wrench”, costs about $10. Big slip-joint pliers ($25) with a 3-1/2 in. jaw opening will work too, plus you can use them for other jobs. Whatever tool you use, you might find that the locknut won’t budge. In that case, a single cut with a hacksaw blade is the only solution. It’s almost impossible to do this without cutting into the strainer threads, so plan on buying a new strainer.
With the locknut removed, pull out the strainer and scrape old putty off the sink with a plastic putty knife. Installing a new strainer is simple. Just remember that the rubber washer goes on before the cardboard washer. Tighten the strainer using the same method you used to remove it.
3. If the pipes are old, replace the whole works
TIP Brush a little Teflon pipe thread sealant on male threads. It lubricates the threads and makes slip nuts much easier to tighten. Check the label to make sure the sealant is safe for plastic.
Some leaks can’t be stopped with straightening or tightening. Stripped nuts won’t tighten and old washers won’t seal because they’re stiff and distorted. You could get new nuts, washers or drain parts. Since plastic pipe is so inexpensive and easy to install, the smart, reliable fix is a whole new drain assembly. You can buy everything you need at home centers for $10 to $15. Kits for side outlet assemblies (like the one shown here) or center outlet assemblies (where the trap is beneath the center of the sink) contain most of the essential parts.
But you might also need:
- Long tailpieces. The tail-pieces that come with kits are often only a couple of inches long.
- A trap arm extender. The arm that comes with the kit may not reach the drainpipe that protrudes from the wall.
- A dishwasher wye that has a connection for your dishwasher hose.
- A disposer kit that allows the waste arm to connect to a garbage disposer.
Here are some pointers for a smooth project:
- You’ll have to cut a few pipes: both tailpieces, the waste arm and maybe the trap arm. A fine-tooth hacksaw works best.
- When in doubt, mark and cut pipes a bit long. Better to cut twice than cut too short and make an extra trip to the hardware store.
- Don’t forget to insert tailpiece washers. Other joints require cone washers. The only joint without a washer is the ground joint at the trap.
- Assemble everything loosely until the whole assembly is complete. Then tighten all the slip nuts.
- Hand-tighten the slip nuts. If any joints leak when you test the new assembly, tighten them slightly with slip-joint pliers.
- When you’re all done, test the assembly for leaks.
4. Install a new adapter on old steel pipe
The drainpipe coming out of the wall has an adapter on the end. This adapter has a washer and slip nut and works just like the other joints in your drain assembly. If your drainpipe is plastic, you shouldn’t have any problems. But if your drainpipe is old galvanized steel, you might run into corrosion that makes the slip nut almost impossible to loosen or retighten.
Here’s how to bypass those rusty old threads: Unscrew the old slip nut. Cut it off with a hacksaw if you have to, but try not to cut deep into the drainpipe’s threads. Buy a plastic trap adapter, a rubber transition coupler, a section of plastic pipe and cement ($10 altogether). The pipe and adapter can be PVC (white) or ABS (black); just be sure to get the right cement for the type of plastic (PVC also requires purple primer). Cement the adapter to a 4-in. piece of pipe and join the plastic pipe to the old metal pipe using the rubber coupler.
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