How to Install a Drain Strainer

A rusty, grimy, or leaking drain strainer can make an otherwise clean kitchen sink look old and unappealing. This small but essential plumbing fixture is the gatekeeper for your sink drain, catching food debris while allowing water to pass through. Many homeowners put off replacing it, assuming it’s a complex job that requires a professional plumber. In reality, it’s a surprisingly straightforward project that most DIYers can complete in under an hour with just a few basic tools.

Learning how to install a drain strainer is a valuable skill that can instantly upgrade the look and function of your sink. This guide will provide clear, step-by-step instructions designed for beginners. From removing the old, stubborn strainer to creating a perfect, leak-proof seal on the new one, we’ll cover everything you need to know to get the job done right.

Why This Skill Is a Great DIY Project

Knowing how to replace a sink drain strainer is a fantastic entry-level plumbing skill that saves you money and builds confidence. A plumber might charge a significant fee for this simple task, but you can do it yourself for just the cost of the new part.

This project immediately improves your kitchen’s appearance, eliminates annoying leaks, and ensures your sink drain is functioning properly. It’s a quick, high-impact home improvement task that delivers a great sense of accomplishment and empowers you to handle other small plumbing repairs around the house.

8 Step-by-Step Guide: How to Install a Drain Strainer

Step 1: Gather Your Tools and Materials

Proper preparation is the key to a smooth installation process. Before you start, gather all the necessary tools and materials. You will need a new drain strainer assembly, which typically includes the strainer body, a rubber gasket, a friction ring, and a locknut.

Your essential tools will be a pair of channel-lock pliers or a specialized strainer locknut wrench, a bucket to catch any residual water, and some rags for cleanup. You will also need a container of plumber’s putty or a modern silicone sealant to create a waterproof seal. Having everything laid out and ready will prevent interruptions once you begin working.

Step 2: Disconnect the P-Trap and Drain Pipe

To access the bottom of the sink drain, you must first disconnect the drain pipes underneath. Place a bucket directly below the P-trap (the U-shaped bend in the pipe) to catch any trapped water. The connections on these pipes are usually large slip nuts that can often be loosened by hand. If they are too tight, use your channel-lock pliers to gently turn them counter-clockwise. You will need to loosen the nuts connecting the P-trap to both the vertical tailpiece coming from the sink and the horizontal pipe going into the wall. Once loosened, the P-trap should slide off easily.

Step 3: Remove the Old Strainer Locknut

With the drain pipes out of the way, you can now work on removing the old strainer. The strainer is held in place by a large locknut on the underside of the sink, pressing against a rubber gasket. This locknut can be the most challenging part of the removal process, as it is often tight and may be corroded.

Use your channel-lock pliers or a strainer locknut wrench to grip the nut firmly and turn it counter-clockwise. You may need to apply significant force. It can be helpful to have a second person hold the strainer from above to keep it from spinning.

Step 4: Remove the Old Strainer Body

Once the locknut is removed, the old strainer should be loose. From underneath the sink, push up on the bottom of the strainer body. It will likely be stuck in place by old, hardened plumber’s putty. You may need to wiggle it or gently pry from the top with a small putty knife to break the seal.

After you remove the strainer, use the putty knife and a cloth to thoroughly clean the sink’s drain opening. Scrape away all traces of the old putty or sealant to ensure the new installation will have a clean, smooth surface for proper adhesion.

Step 5: Apply Plumber’s Putty or Sealant

Now you are ready for the new installation. Take a small amount of plumber’s putty and roll it between your palms to create a soft, pliable rope about the thickness of a pencil. Apply this rope of putty evenly around the underside of the new strainer’s top flange—the part that will sit inside the sink.

This putty is what creates the watertight seal between the strainer and the sink surface. If you are using silicone instead of putty, apply a continuous bead of silicone in the same location. This sealant application is a crucial part of learning how to install a drain strainer.

Step 6: Set the New Strainer and Install the Gasket

From the top of the sink, press the new strainer firmly into the drain opening. The plumber’s putty should squeeze out evenly around the edges, which indicates you have a good seal. From underneath the sink, slide the new rubber gasket and then the friction ring (if included) up over the threads of the strainer body. The rubber gasket should be pressed firmly against the underside of the sink. This gasket provides a secondary seal and cushions the locknut against the sink material, which is key to a successful installation.

Step 7: Tighten the New Locknut

With the gaskets in place, thread the new locknut onto the strainer body from below. Hand-tighten it as much as you can, ensuring it is not cross-threaded. Then, use your pliers or strainer wrench to give it a final tightening. It needs to be very snug to compress the putty and the gasket, but be careful not to overtighten, as you could crack the strainer or the sink.

As you tighten the locknut, it’s helpful to have someone hold the strainer from above to prevent it from turning and smearing the putty seal. This is the most important step for how to install a drain strainer securely.

Step 8: Reconnect the Drain Pipes and Test for Leaks

With the new strainer securely installed, it’s time to reconnect the plumbing. Re-assemble the P-trap and the drain pipes, tightening the slip nuts by hand first and then giving them a final quarter-turn with your pliers. Now, remove the excess plumber’s putty that squeezed out from around the strainer’s flange inside the sink. Place the new strainer basket in the drain, fill the sink with a few inches of water, and then let it drain while you watch the pipes below for any drips. Check carefully around the new locknut and all pipe connections.

Common Installation Mistakes

When installing a sink strainer, there are several common mistakes that can lead to issues down the line. One frequent error is failing to properly tighten all connections. Slip nuts or the locknut may not be secured enough, resulting in leaks once water flows through the system. Another mistake is not using an adequate amount of plumber’s putty or overusing it, which can prevent a proper seal around the flange.

Additionally, misaligning the pipes during reassembly can cause stress on the connections, leading to potential leaks or even cracked fittings. Lastly, neglecting to check for leaks after installation is a common oversight—taking the time to inspect thoroughly can save significant effort in repairs later. Being mindful of these details ensures a successful and leak-free installation.

Frequently Asked Questions (FAQ)

Should I Use Plumber’s Putty or Silicone to Seal the Strainer?

Both can work, but plumber’s putty is the traditional and often preferred choice for this job. It remains pliable, making future removal easier, and it will not damage plastic sinks or fixtures. Silicone creates a stronger, more permanent adhesive bond, which can be good for preventing leaks but makes removal extremely difficult. For a standard stainless steel or cast iron sink, plumber’s putty is the recommended choice for a reliable, non-permanent seal.

My Old Strainer Is Spinning When I Try to Loosen the Locknut. What Do I Do?

This is a very common problem. The easiest solution is to have a helper hold the strainer still from inside the sink. If you are working alone, you can insert the handles of a pair of pliers or a large screwdriver into the crossbars of the strainer from above. You can then hold this tool with one hand to provide counter-torque while you use your other hand to turn the locknut from below.

The New Strainer Came with a Cardboard Ring. What Is It for?

The cardboard ring is a friction ring. It is designed to be placed between the rubber gasket and the metal locknut. Its purpose is to allow the locknut to be tightened smoothly without grabbing and twisting the rubber gasket out of place. This ensures the gasket sits flat against the sink and creates an even, secure seal. Always install the parts in the correct order: rubber gasket first, then the friction ring, then the locknut.

How Tight Should the Locknut Be?

The locknut needs to be very snug to compress the plumber’s putty and create a watertight seal, but overtightening can cause problems. A good rule of thumb is to hand-tighten it as much as possible, and then use your wrench to give it another half to a full turn. You should see the plumber’s putty squeeze out evenly from the top. If you are using a lot of force and the nut won’t turn, it’s likely tight enough.

Can I Reuse the Old Drain Pipes?

Yes, as long as the old P-trap and connecting pipes are in good condition and not cracked or corroded, you can absolutely reuse them. Just make sure the rubber slip-joint washers inside the connection nuts are still soft and pliable. If they are old, hard, or cracked, it’s a good idea to replace them with new ones to ensure a leak-free connection.

Conclusion

Knowing how to install a drain strainer is a practical skill that immediately improves the look and function of your kitchen sink while saving you from a costly plumbing bill. This task, which may seem daunting at first, is quite manageable when you break it down into simple, logical steps. With a bit of patience and the right tools, you can successfully replace this crucial plumbing fixture and achieve a professional, leak-free result.

Now that you have the knowledge, you can approach this project with confidence. Say goodbye to that old, leaky strainer and enjoy the satisfaction that comes from completing a home improvement project with your own two hands.