Demystifying Common Kitchen Sink Drains

Kitchen sink drains play a critical role in removing water and waste from the sink basin. With so many components working together, it's easy for home cooks to feel mystified when something goes wrong. Understanding the basic types of drains and how they operate is the first step to keeping your kitchen flowing smoothly.

You'll learn how each piece fits together to whisk away water without a trace. We'll also cover maintenance tips to prevent clogged drains and leaky joints.

Continuous Waste Assembly

What is a Continuous Waste Assembly?

A continuous waste assembly is a complete sink drain system composed of slip-joint pieces that connect without any seals or washers. This single, seamless unit includes the strainer basket, tailpiece, and slip-joint nut.

Unlike traditional assemblies, a continuous waste has no joints that can come loose or leak over time. The uninterrupted drainage path also maximizes flow. Fewer parts mean fewer opportunities for clogs to form.

Installing a Continuous Waste Assembly

Putting in a continuous waste assembly takes more initial effort but prevents maintenance down the road. Start by removing existing connections and drain baskets. Apply plumber's putty around the drain opening. Insert the assembly into the sink drain hole, then tighten and lock the strainer basket in place.

Next, you'll need to adjust the assembly height by cutting the tailpiece. Connect the end of the tailpiece to the p-trap. Don't overtighten the slip-joint nut. Test for leaks before using the sink.

P-Traps

What is a P-Trap and How Does it Work?

A p-trap is the curved section of drain pipe designed to hold water and prevent sewer gas odors from entering living spaces. As the name suggests, a p-trap takes the shape of the letter "P" with the bottom curve acting as a water seal between the sink and waste line.

The water sitting in the base of the p-trap blocks gases and odors. But it also allows waste water to pass through to the main plumbing drainage system. The p-trap is a simple but critical component in any sink's plumbing.

P-Trap Installation and Maintenance

Connecting a p-trap starts by mounting it to the sink drain assembly using slip-joint washers. The other end attaches to the waste line. If needed, use transitional fittings to match different pipe sizes.

P-traps rarely need replacement, but they should be cleaned periodically to remove built-up gunk and debris. You can disassemble the slip joints by hand to access the inside. Be sure to re-fill the trap with water once reassembled to reestablish the seal.

Tailpieces

Tailpiece Function

The tailpiece is the short, vertical section of pipe that connects the basket strainer to the p-trap below. This simple but important plumbing piece transports water from the sink basin down to the curved trap.

Choosing the Right Tailpiece

Tailpieces come in plastic or metal, with plastic being the most common. You'll need to choose the right length and width to match your sink basin and strainer size. Tailpieces are usually 1.5 inches in diameter but you can get narrower or wider sizes if needed.

Cut a plastic tailpiece with a hacksaw for a custom fit. Use a deburring tool to smooth cut edges. Follow the package directions to assemble slip-joint tailpieces.

Slip-Joint Connections

How Slip-Joints Seal But Allow Disassembly

You'll find slip-joint washers in places where drains must be sealed but also come apart easily. Slip-joint connections use compression to create a tight friction fit between two pieces of pipe or drain components.

A slip-joint nut threads onto one end of the fitting. Tightening the nut pushes a beveled compression washer against the inserted pipe. This metal-on-metal contact secures the joint. Loosen the nut to disassemble when needed.

Using Slip-Joints Correctly

Common spots for slip-joints are the connections to the sink tailpiece, p-trap, and trap arm. You can hand-tighten slip-joint nuts, but don't overdo it. Snug is tight enough.

Check for leaks after reassembling slip-joints. If needed, tighten the nut gently with pliers a quarter turn at a time until the drip stops.

Garbage Disposals

How Garbage Disposals Work

Garbage disposals are installed under the sink on the drain line. They grind up food particles entering the drain so they can pass through plumbing without clogging. Disposals have a motor that spins shredder blades at high speed whenever activated.

Most disposals have a switch that controls power. Some turn on automatically when the sink drain opens. An inlet opening connects to the sink drain, while the outlet joins to the drain pipe.

Installation Tips and Precautions

Hardwiring a disposal into the switch and electrical system is recommended over plug-in models. Using the dishwasher drain hose as the disposal outlet eliminates an additional connection point.

Don't forget to knock out the drain plug inside the disposal inlet. Avoid putting certain items down the disposal like grease, eggshells, or fibrous produce. Run plenty of cold water when grinding food waste.

Drain Stoppers

Types of Sink Drain Stoppers

Drain stoppers seal the sink opening to allow filling the basin with water. Popular styles include lift-and-turn, pop-up, and push-button assemblies. Stoppers are raised and lowered by rods or links under the sink.

A lift-and turn stopper rotates to seal the drain or unlock for opening. Pop-up stoppers raise or lower vertically. Push-button mechanisms attach to the sink with suction and control a rocker-arm stopper.

Choosing and Maintaining Drain Stoppers

Match the stopper style to your existing sink hardware. For vessel and undermount sinks, pop-up assemblies mount through the counter. Adjust stopper rods as needed if the seal is too loose or tight.

Clean hair and gunk from sink stoppers regularly. Disassemble linkages to access stuck pop-up stoppers. Replace worn out drain stoppers that cannot form a good seal.

Overflow Drains

Purpose of Overflow Drains

An overflow drain is an extra drain path above the main sink drain opening. It serves as a backup to prevent water from overflowing the counter if the sink basin fills too high.

Overflow drains typically tie into the main drain line. They remove excess water before the sink can overflow and cause a mess on counters and floors.

Installing an Overflow Drain

Adding an overflow during sink installation is easiest. Drill a hole at the desired height for the overflow outlet. Connect tubing to the overflow drain body, then run it to the p-trap or tailpiece.

Choose a style - some overflow drains screw into place, others slide into a hole. Make sure the gasket seals tightly. Adjust the height and position as needed.

With so many individual components, kitchen sink drains may seem complicated. But understanding how the main pieces like tailpieces, p-traps, and slip-joints work makes it easier to keep drains clear and functioning.

Continuous waste assemblies, garbage disposals, stoppers, and overflow drains each serve unique purposes. Proper installation and maintenance will extend the life of your kitchen sink plumbing.

If drain problems persist, don't hesitate to enlist the help of a professional plumber. With the right parts and care, your kitchen sink drains will provide years of clog-free service.