Dry air might just be the cause of that unpleasant rotten egg smell in your home. Especially during winter, a P-trap can dry up and allow sewer gas to enter the home. ... Since P-traps can dry out in as little as a month in the wintertime, doing this periodically will help prevent the problem before it starts.

Is AP Trap supposed to hold water?

In a nutshell, a p-trap is a u-shaped bend in the waste pipe that connects a sink's drain to a home septic tank or to a municipal sewer system. Under normal circumstances, p-traps always contain some water.

Why is my P-trap dry?

Dry p-traps occur when the trap or interceptor has lost its water seal, allowing sewer gases to build back up through the drain and into your home. Leaky p-traps can start as something small and turn into something much bigger if the leak isn't fixed right away.

How do I know if my P-trap is dry?

You can open up your under-sink cabinets and see the P-trap right away; it's a U-shaped pipe and can be either PVC or stainless steel. The P-trap needs to have water in it to keep smells and flammable gases at bay, so if it runs dry, you'll notice.

How do you fix a dried out p-trap?

It is easy to fix a P-trap that ran dry due to a period of inactivity. Flush the unused toilet and pour water down the sink and bathtub drains to restore the P-trap's water barrier. Run water down the infrequently-used bathroom drains regularly to prevent the P-trap from running dry in the future.

How a Plumbing Trap Can Lose Water | Ask This Old House

17 related questions found

How do I add water to my P-trap?

Fortunately, there's an easy fix to this problem: just fill the P-trap with water again. To do this, walk around your home with a pitcher of water and pour water down every drain you can find. Showers, bathtubs and sinks that see regular use probably have water in the P-trap already.

How do you get rid of dry trap smell?

If you smell a funny stench or odor coming from your floor drain, it's very likely your P-trap is dry. Simply pour a few gallons of water to re-establish the proper water barrier. You can add a small amount of vinegar to help remove any persistent odors.

How do you check AP traps?

Twist the Collar Ring, and Look Inside

Grab the collar ring and twist counter-clockwise. Slide it down, empty the water and look inside. If the P-trap is not clogged, the problem may be deeper in the drain line.

Why does my whole house smell like poop?

A regular sewer-gas smell is just a bad stink with a definite odor of feces and sometimes a rotten-egg (hydrogen sulfide) smell and/or a moldy mustiness too. ... because an empty or 'dried-out' P-trap is by far the most common cause of all sewer-gas smells.

What does dry P-trap smell like?

Dry P Trap

A dried p trap will result in a sewer odor emitting from a sink that maybe hasn't been used in a while.

What is a dry trap?

A dry trap. This is the most common cause of sewer odors. ... The trap collects and holds a small amount of wastewater, and it is this wastewater that prevents sewer gases from coming through the drain and releasing odors into the building.

Does AP trap have to be directly under the drain?

The "P" trap SHOULD be directly under the drain, but no more than a few inches off center of it, if conditions require it. NO trap, TWO traps, and/or a 9 foot offset are NOT allowed and if he suggests any of them get a different installer who is a REAL plumber.

Can AP trap get clogged?

A blocked p-trap will cause water backflow to occur. The first sign that your p-trap is clogged is when the water in your sink takes longer than average to flow down the sink. In the case of a clogged P-trap, it is best to place a small bucket under the trap with the water shut off.

Do you need AP trap for washing machine?

When hooking up a new washing machine, some people look for a convenient drain line and simply install a pipe that extends to the washer. ... The lack of a P-trap exposes the area to sewer fumes and the lack of venting will cause the drain to run sluggishly and overflow. Washers, like all fixtures, need a trap.

Does AP trap need a vent?

P-traps need vents

1 – They give the sewer gases a place to vent, so they do not build pressure inside your sewer lines. 2 – They prevent siphoning of the water out of the trap.

How far can ap trap be from vent?

trap, the distance from the weir of the trap to the vent pipe opening “shall not” exceed 30 inches.

Do you vent before or after trap?

Plain and simple, the vent comes AFTER the trap. A vent before the trap does absolutely nothing. The open drain inlet at the bottom of the sink is the vent before the trap. It is why fixtures do not need ANY vent to drain, they need a proper drain to not siphon the trap.

Why does my house smell like sewage when it rains?

Raining often causes atmospheric pressure changes, which can lead to the air becoming heavy. As such, the methane gases typically found in the septic tank don't flow through the vent as they normally would. Instead, they stay low to the ground, causing a foul smell similar to rotten eggs.

Why do I smell sewer gas after a shower?

Leaky Pipes

Leaky pipes in your bathroom walls or under the shower will allow sewer gases — also known as hydrogen sulfide — to escape, so you may notice the shower drain smells like rotten eggs or sewage.

How does a trap lose its seal?

Pressures above or below that design pressure will cause a trap to lose its water seal. A positive pressure on the downstream side of the trap will cause air to blow through the trap seal, pushing its contents into the fixture. A negative pressure will siphon the trap seal into the trap arm and the drain.

Is there supposed to be water in shower drain?

2 Answers. Yes it's normal and what you want. It's called a P-trap and the water sitting in there seals out the sewer gasses.

What is a dry sewer?

When a drain pipe is subjected to a prolonged period of inactivity, it may begin to dry out. ... The real culprit of dry drain is the debris that are inside. When the drain is used again, the water will loosen all the debris, which can then result in a clog in your drain or in the main sewer line.