Strainer Basket in Kitchen Sink STILL leaking

My kitchen was renovated 6 years ago. From almost the very beginning the strainer basket has been an issue, started leaking very slightly after 3-4 months, contractor came back reinstalled with more plumbers putty and said the nut holding it had loosened. Kept happening ever since and I finally replaced that strainer basket because the nut just wouldn’t stay tight. Same issue with new basket. Keeps leaking. I’m starting to think it’s something about the sink itself. Anybody have a guess?

 

What kind of sink?

Was the strainer installed exactly as the instructions show, there are different types of gaskets that get installed in specific locations and may even be based on the sink material!

 

Kitchen sink. Strainer Basket(s) x3 have been installed by professional plumbers x2 and once by myself. All have leaked. As far as I know all we’re installed exactly as they should have been.

 

Yes... we know it's the kitchen sink.
What type of sink.... stainless steel, porcelain, etc ?
What is it made of ?

Stainless steel sinks are very thin and can be a little difficult to seal.
There needs to be putty on the top and a rubber washer underneath with a metal washer and nut.

 

Sorry, it is stainless, didn’t realize I hadn’t actually said that. And it does have plumbers putty above and rubber washer below, as well as the cardboard “washer”.

 

Stainless Steel sink, all washers in place and plenty of plumbers putty; Yet it's still leaking - is there anything I can do, short of replacing the sink with Porcelain? It's undermounted, D-shaped and 9" deep and it was not an inexpensive sink 18 gauge Elkay. Any suggestions are welcome. Thank you all and Happy, Healthy and Peaceful Holidays to all.

 

Is it leaking from the joint between the basket and sink or from the PVC adaptor screwed to the basket?

Many years ago I had similar issue, could not get that damn basket to stop leaking. On my 4th trip to hardware store an older employee showed me how the PVC coupling on the down pipe that was part of the drain assembly was very thin, suggested a individual piece that was much thicker and robust. The part was not sealing properly to the threads and it wasn't real obvious exactly where the leak was at.

Clearly something that he had seen before but Problem Solved!

 

It's always seemed like it's from the strainer basket/sink joint - but it is kind of hard to actually tell - it's so minimal, but pervasive. Minimal in that I leave a folded piece of Bounty Paper towel on the base of the cabinet centered under the drain and change it every 3-4 days. It's always damp but rarely saturated. It's just so annoying and frustrating. I'll investigate further next week when I have the time and energy. Thanks for the suggestion.

 

If you've been using plumbers putty, switch to silicone instead.

 

I always hated those strainer baskets with the nut, there is no good way to hold the basket and tighten the nut from below so it's no wonder it isn't tightened enough. Years ago I switched to a slightly different style strainer basket with thee screws similar to how an ISE disposer mount attaches to a sink. With this style one person can do the entire job.

https://www.lowes.com/pd/Keeney-3-5-...cluded/3132177

Kohler makes a similar basket with a lot higher price.

https://www.lowes.com/pd/KOHLER-Duos...sposal/3664970