It is highly likely you mean a P-trap (a plumbing component shaped like a "P") rather than an "AP trap". P-traps are essential to keep your home safe, sanitary, and odor-free.
Use a P-trap for virtually any plumbing fixture with a drain—such as sinks, showers, bathtubs, and washing machines. It is placed beneath the fixture to block noxious, potentially hazardous sewer gases and foul odors from venting into your home.
The "135-degree rule" in plumbing states that the total (aggregate) horizontal change in direction for a drainage pipe—specifically trap arms—cannot exceed 135 degrees between the P-trap and the vent. Exceeding 135 degrees (such as using three 45-degree bends or a 90 and two 45s) requires a cleanout because sharp turns hinder flow and cause clogs.
While S-traps may still be found in older homes, they're increasingly considered outdated and less effective. P-traps, on the other hand, have become the universal standard thanks to their superior design, ability to maintain a water seal, and compliance with modern building codes.
Common fixtures that require P-traps
All plumbing fixtures that connect to your drainage system require P-traps, including: Bathroom sinks and vanities. Kitchen sinks and garbage disposals. Utility and laundry sinks.
Without a P-trap, toxic sewer gases (like methane and hydrogen sulfide) bypass the pipe and vent directly into your home. This introduces foul odors, poses serious health risks, and is an immediate code violation. In some setups, like air conditioners, it can also cause severe indoor flooding.
Yes, a toilet, shower, and sink can share the same main sewer or drain line, but they must use independent branch lines that connect below the floor. Directly tying a sink or shower drain into a toilet drain behind the wall violates code and risks severe backflow and clogs.
Over time, repeated use of chemical cleaners can weaken pipe walls, warp plastic piping, and corrode older metal lines. This gradual damage often leads to leaks, cracked pipes, and sudden plumbing failures that require emergency repairs. Another problem is that drain cleaners do not solve the real cause of most clogs.
The most popular and effective P-trap alternative is the HepvO Sanitary Waste Valve, a waterless, self-sealing membrane that blocks sewer gases. Other options include flexible drain kits for tight spaces, rigid space-saver traps (like bottle traps), and sharing a trap with an adjacent sink.
A straightforward yet effective approach to addressing a clogged drain pipe involves simply using hot water mixed with dish soap. This method, ideal for tackling minor blockages, leverages the degreasing power of dish soap combined with the force of hot water to dislodge and dissolve clog-causing residue.
To protect your plumbing and the environment, you should never put fats, starches, harsh chemicals, or solid waste down your drains.
Here are the most common plumbing code violations you might not even realize you have—and why they matter.
Yes, a toilet and a sink can share a vent. In modern plumbing, this is most commonly done using a wet vent, where the sink’s drainpipe also acts as the vent for the toilet.
Yes, water is supposed to stay in a P-trap. The curved shape of the pipe is specifically designed to hold a small amount of water after every use. This standing water creates a vital, airtight seal that prevents foul-smelling and hazardous sewer gases from coming up through your drain.
[DIVERSE COMPATIBILITY] Our sink p trap kit is compatible with many types of under sink installations for kitchen and bathroom sinks that measure 1 1/2 or 1 1/4 inches in outer diameter.
The purpose of the p-trap is to catch water in the dip in the pipes and keep it there. After you run water down the drain, gravity will keep a plug of water in the dip. (The maximum trap seal depth is 4”.)
It is a code requirement that every fixture must be trapped. A p-trap is one type of trap, while a drum trap is another. In most cases, a p-trap is the preferred option. If the fixture is not trapped, sewer gas can enter the living space.
No, you cannot use WD-40 instead of plumber's grease.
Sealers and compounds are essential plumbing consumables designed to ensure leak-proof connections and long-lasting performance in both domestic and commercial settings.
As the fall rains intensify and the seasons shift, one surprising tip is getting renewed attention: pouring vinegar down your drains to help prevent clogs.
Plumbers use a variety of specialized tools depending on the severity and location of the clog. They typically start with a heavy-duty plunger or a manual drain snake, and will escalate to professional motorized augers and hydro-jetting machines for stubborn or deep blockages.
People don't typically dispose of cleaning products - they use them up. Empty packages can then be recycled or discarded with other household waste. Unused amounts of cleaning products can generally be safely disposed of down the drain or in the trash.
Many traditional Old Order Amish communities view store-bought toilet paper as an unnecessary indulgence or luxury. Instead, they rely on readily available, sustainable alternatives like crumpled-up old newspapers, mail-order catalogs, corn cobs, and cloth rags, though more progressive groups now commonly use conventional toilet paper.
Pouring salt down your drain at night is a popular DIY plumbing trick used for routine maintenance. The goal is to take advantage of the salt's coarse texture and natural moisture-absorbing properties.
Yes, Dawn dish soap can help unclog drains, but primarily only for minor blockages caused by grease, soap scum, or oily residue in kitchen and bathroom sinks. Its powerful degreasing properties work to break down the fats causing the restriction, especially when paired with hot water.