Bathroom Sink Drain Leaking

Bathroom Sink Drain Leaking

Bob Jackson January 18, 2017 at 9:08 pm # Is your drain leaking? The drain overflow holes are for sinks with an overflow outlet (hole) near the top the bowl. If the water level rises too high it will run out through the bowl overflow through a channel inside the bowl to the drain overflow holes, then down the drain pipe. This prevents the sink from filling completely up and flooding. If the sink bowl doesn’t have an overflow hole then the drain overflow holes serves no purpose. My sink bowl doesn’t have an overflow. I installed the drain with an overflow because that was the available replacement model available at the hardware store. The original drain installed by the home builder had overflow holes. Reply
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Bathroom Sink Drain Leaking

If the drain pipe under your bathroom sink is leaking, you may need to simply re-tighten the nut. If no Plumbers Putty was used when installing the drain outlet flange in the sink, this is another reason it may be leaking. You may also have the gasket or rubber sealing washer that goes between the nut and the sink overtightened and this is causing the leak. The gasket or rubber sealing washer may not be completely flat and therefore not sealing. Check to see if you are able to tighten the nut with another half turn or so and check for leaks. If no matter how tight the nut is and it still leaks, take everything apart including the drain pipe and the drain outlet flange in the sink.
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Bathroom Sink Drain Leaking

How to fix it: To repair a tub drain, unscrew the drain flange from above. Then clean the flange and apply silicone caulk. Also remove the rubber gasket that’s under the tub’s drain hole and take it to a home center to find a matching gasket. Slip the new gasket into place and screw in the drain flange. If you have access to a shower drain from below, tighten the ring nut that locks the drain to the shower pan. If that doesn’t work, replace the drain assembly. If you don’t have access beneath the drain, cut a hole in the ceiling below or replace the drain assembly with a WingTite drain.
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Bathroom Sink Drain Leaking

Hi Del, Another reader and I experienced the same problem with the plastic sink drain. I believe the problem is the plastic sink drain isn’t strong enough to seal the rubber gasket. Replacing the cheaper plastic drain with the all-metal Dearborn Brass 1-1/4″ pop-up drain Model # H759BN-3 fixed the problem. (Revision: Home Depot’s new part # is the Everbilt C759-1 brass metal drain for the former Dearborn H759BN-3. However, the C759-1 specification sheet is branded Dearborn Brass.) I’ll update the project with a notice to use the metal drain because three people (including yourself) have reported problems with the plastic drain leaking. Thanks, Bob Reply
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Bathroom Sink Drain Leaking

How to reinstall the sink drain WITHOUT any leaks… (Be sure all parts are removed, clean, and not damaged) 1 – Add a 1/2″ thick ring or rope of Plumbers Putty to the underside of the top flange of the sink drain. (Warm the putty up with your hands first to make it easier to use – Be sure the Plumbers Putty is in a continuous circle) 2 – Apply some Plumbers Tape to the threads of the drain. 3 – Use enough Plumbers tape to cover the threads near the area where the nut will be positioned when fully tightened. 4 – Spin the nut all the way down or off of the threads. 5 – Insert the drain back into the sink hole and be sure it is centered. 6 – Install the nut and the sealing washer and tighten. (The excess putty will ooze out under the top flange until it is fully seated to the sink) 7 – Remove the excess putty from in the sink. 8 – Add Plumbers Tape to any areas of the drain pipe that has threads. 9 – Reinstall the drain pipe making sure it is centered and not overtightened. 10 – Run the bathroom faucet and check for water leaks under the sink.
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Bathroom Sink Drain Leaking

If you can’t pinpoint the source of the leak, it’s fair to suspect the sink drain, which only leaks when the sink is full of water, or the faucet. If it’s the sink drain that’s leaking, unscrewing it and repacking it with plumber’s putty will usually fix the problem. Although you usually notice faucet leaks above the sink, sometimes water can flow down the back of the faucet and drip underneath the sink without being visible. The procedure for fixing a leaking faucet depends on the type of faucet you have. It usually involves disassembly and replacement of one or two gaskets or washers.
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Bathroom Sink Drain Leaking

Fixing Other Leaks If you can’t pinpoint the source of the leak, it’s fair to suspect the sink drain, which only leaks when the sink is full of water, or the faucet. If it’s the sink drain that’s leaking, unscrewing it and repacking it with plumber’s putty will usually fix the problem. Although you usually notice faucet leaks above the sink, sometimes water can flow down the back of the faucet and drip underneath the sink without being visible. The procedure for fixing a leaking faucet depends on the type of faucet you have. It usually involves disassembly and replacement of one or two gaskets or washers.
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Bathroom Sink Drain Leaking

Although it may seem like a lot of work, the best option is to take the drain apart and reassemble it. Trying to patch the leak will likely only stop it for a short time, you’ll then end up with a possibly unnoticed leak sometime in the future. This unnoticed leak can lead to massive amounts of water damage, and far more work in the future. Do it right now, and never worry about it again. Silicone is great stuff and is very useful for a lot of things, but it is not the fix-all-do-everything product people like to think it is. As you’ve seen, silicone is not the best option for sealing drain flanges. Disassemble the drain. Scrape all the silicone off the sink and flange. Roll out a good size bead of plumbers putty around the sink flange lip. Seat the drain flange in the putty. Tighten the drain retaining nut. Remove the excess plumbers putty that squeezes out. Repeat steps 5-6 until the drain is adequately tight. Enjoy a leak free drain.
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How to find the source: If you can see the underside of the drain through an access panel or open ceiling, partially fill the tub and then release the water. In a shower, plug the drain with a rag and then release the water. Check the drains and traps for leaks from below through the access panel. If you don’t have access to the underside of the drain, plug the drain and add enough water to form a small puddle around the drain (photo). Mark the edge of the puddle by setting a bottle of shampoo next to it. Then wait an hour. If the puddle shrinks, the drain is leaking. Don’t rely on your tub stopper for this test; it may leak. Remove the stopper and insert a 1-1/2-in. test plug (find them at home centers). Remove the grate and use a 2-in. plug for a shower.
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Bob Jackson August 6, 2016 at 12:47 pm # If you take apart the drain and place the flange in the sink without plumber’s putty, does the flange sit fully in the sink recess? If not the flange is too thick and you’ll need to find the pop-up drain fits the profile of your sink. Likely by purchasing the drain made by your sink manufacturer. “Less putty?” – I doubt using less putty will fix it if the drain is tight. Putty squeezes out fairly easily so a little too much corrects itself. Reply
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If the sink drain hole was thoroughly cleaned of the old plumber’s putty, my guess is the plastic lock nut isn’t strong enough to evenly seal the rubber gasket against the sink bottom and is warping. Sometime after this project, I replaced the pop-up drain in another bathroom with the same plastic body Dearborn Brass 1-1/4″ Pop-Up Sink drain model #H756-1 and like you, could not get the rubber gasket to completely seal not matter how much I tightened it. A very slow drip was always present. I initially tightened the lock nut to what should be sufficient… it leaked. Tightened it some more, still leaked very slowly. Removed the drain, cleaned all surfaces again, reinstalled it and it still leaked, maybe a drop or two every couple of minutes. Waited a day for the parts to settle in, it still leaked and really cranked down on the lock nut until I thought I might crack the plastic. It still leaked!
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Bob Jackson November 23, 2014 at 12:52 pm # You didn’t mention the specific drain model #, but I’ve also had problems with the less expensive plastic drain leaking no matter how much I tightened it… and you can only tighten it so much without damaging it. I think the plastic drain just isn’t strong enough and may warp causing a leak. See this comment where I replaced the chromed plastic drain with an all-metal unit that fixed the leak. Reply

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