Replace a leaking basket strainer only after confirming the leak is at the sink-to-strainer seal or damaged strainer body, rather than the tailpiece or trap. Match the replacement to the sink and follow its gasket and sealant instructions. Support connected piping, avoid overtightening, and check the repair with both standing and draining water.
Separate the strainer seal from the lower drain
The flange sits inside the sink bowl. Its seal keeps water from escaping around the outside of the strainer. The tailpiece below has a separate connection, and the P-trap has its own washers. A repair to one joint does not fix the others.
For the initial timing check, see water leaking under a sink. If the sink has a garbage disposal in that opening, it uses a disposal mounting assembly instead of an ordinary basket-strainer body; follow the disposal's instructions rather than this replacement plan.
Match the replacement and sealant to the materials
Check the sink opening, sink material and the replacement manufacturer's requirements. Oatey's basket-strainer guidance says brass and stainless components can use silicone or putty, but the sink manufacturer must also approve the sealant. It warns that regular putty can stain porous sinks and calls for silicone on its plastic strainers because putty can cause failure.
Kohler's cited stainless-sink guide directs users to the drain fitting's own installation instructions. Its putty note applies to the covered stainless-sink installation, not every stone, composite or plastic component. Do not make a general rule from the fact that an old strainer had putty beneath it.
Remove and reseal without twisting the piping
Empty the sink and stop using the connected drain. Put a catch container underneath. Follow the strainer's instructions to disconnect the tailpiece, support the drain and remove the retaining hardware. Stop if corrosion or inaccessible fittings prevent removal without force.
Clean the mating surfaces and install the replacement with its specified sealant, gasket order and fastening method. Do not reuse hardened sealing material or improvise a washer stack. Hold the body as directed while tightening so connected piping is not twisted. Slip-joint drain connections seal with their washers, as Oatey's P-trap guide explains; thread tape is not a substitute.
Test the repaired joints
Check beneath the flange with water held in the bowl, then drain the bowl while inspecting the lower connections. Follow any required sealant cure time before wet testing. A recurring drip needs the joint checked again, not progressively harder tightening. Installing a kitchen sink covers the surrounding connections, and what a P-trap does explains the lower drain assembly.