In case you’ve ever cleared a clogged sink drain, then you’re probably familiar with a sink drainage p-trap. The P-trap assembly is the section of the sink drain that connects the sink drain to the main drain system at the wall.
The sink drain trap is often known as a P-trap, thanks to its curved shape. It’s actually the curved fitting you see right below the sink.
Drain traps are usually made from different pipe materials. Most modern traps are made using PVC, which is a form of plastic. Traps are also made of ABS plastic, brass, copper, or chrome.
The components of the trap are normally joined with slip fittings that are easy to disassemble or assemble. Some plastic traps are solvent glued while some metal traps may be soldered.
In exposed sink drains, such as pedestal sinks, brass or chrome trap fittings are the most preferred option. Sinks drains that are hidden within vanities or base cabinets are often made of PVC.
Modern PVC traps are less prone to issues. They often last for several decades. However, older traps made of chrome are prone to corrosion and rusting. Thus, replacing chrome traps is a common DIY home improvement project.
At times, you may have to replace the trap when replacing the sink, especially when the new sink configuration is different from the existing trap configuration.
The Basic Anatomy of a Drain P-Trap
The sink trap comprises of two components: the waste arm and the p-trap bend.
- Trap bend– The bend is usually U-shaped. One end of the bend is connected to a vertical tailpiece. The other ending is connected to the trap arm. Luckily, the bend can be removed easily to clear any clogs. Some bends have a cleanup fitting at the bottom.
- Waste arm– It’s also known as a J-bend or trap arm. It’s a piece of pipe that is connected to the trap bend on one ending and to the main drain within the wall on the other ending.
The Role of a Drain Trap
Just like its name, the P-trap is P-shaped. It plays an import role in how the sink drains water. The trap bend is curved in such a way that it traps some little water as it flows down the sink drain.
The trapped water creates a seal which prevents sewer gases from flowing into the house. However, the bend is prone to getting clogged. As such, it’s designed for easy disassembling as needed to clear clogs.
The trap components are connected with some slip fittings for easy disassembling and assembling. You can also remove the trap to snake the drain in case it develops a serious clog.
Replacing the P-Trap
You can easily find a P-trap replacement kit from your local hardware store. The kit comes with all the important parts. Ensure the kit you’ll buy matches the existing P-trap with respect to configuration and pipe diameter.
For instance, some kits are specially designed for use on a double kitchen sink while others are ideal for sinks that have garbage disposals.
With time, it may become necessary to replace brass or chrome traps with PVC traps. However, ensure the diameter of the new fitting matches with that of the old fitting. Most drains use a 1 ½ or 1 ¼ inch diameter P-trap.
Tools and Supplies Needed
- Slip-joint type of pliers
- P-trap kit
- PVC cutter or hacksaw (if necessary)
Step 1- Removing the old P-trap
First, take the bucket and place it under the trap. It will catch any spillage when disassembling the trap. Next, loosen the nuts that hold the trap bend in place using the slip-joint type of pliers.
Once you’ve loosened the fitted slip nuts, the bend will slid off easily. In case it doesn’t slide off, wiggle it gently until it becomes loose.
Next, loosen the nut that holds the trap arm in place. Then slide off the trap arm from the drain opening. Wiggle it gently if necessary. Keep the parts you have removed aside.
Step 2- Attaching the new trap arm
Unpack the new trap kit. Take the new slip nuts and slide them on the trap arm. One nut should be placed at the trap arm ending with a curve.
The other slip nut should be placed at the straight ending of the trap arm. The open threads of the nuts should face outward. Next, slide the slip washer on the straight ending of the trap arm with the bevel facing outward.
Slide the straight ending of the trap arm into the drain opening to test whether it fits properly. It should allow for some space to slide it inward and outward of the drainage opening to adjust its length.
Next, slide the nut over the threaded ending of the drainage opening. Don’t tighten the slip nut completely yet since you might need to make adjustments later on.
Step 3- Attaching the drain trap bend
Now slide the nut over the sink drainage tailpiece. Next, slip the washer. When inserting the washer, its beveled ending should face downward.
Next, slide the drain trap bend over the tailpiece. Position the bend in a manner that the opposite ending takes in the curved ending of the trap arm.
Adjust the trap arm inward and outward of the drainage opening if necessary. Once done, tighten the slip nut on the tailpiece lightly.
Also, tighten the slip nut on the trap bend lightly. Tighten them in an alternating manner until the slip washers are tightly fitted in place.
Useful tips: At times, the trap arm might be longer than the existing sink configuration. In this case, you may cut the straight section of the trap arm to a matching size.
Use a PVC cutter or hacksaw to cut the trap arm. Some kits may come with trap arms of various sizes to make the installation work easier.
Step 4- Tightening the trap fittings and testing the drain
Once the p-trap fittings are in place and fit correctly, tighten the slip nuts using the slip-joint type of pliers. However, avoid over-tightening them. Once you hard-tighten them by hand, tighten them another quarter turn with the pliers.
Next, open the sink faucet and allow water to run. Check the drain fittings for any leakage. In case there’s any leakage, simply tighten the nuts a little bit more.