If you don't run any water down the drain for a long time, the water inside the P-trap will eventually evaporate. It usually takes a month or more before the trap will fully dry out.
P-traps are supposed to hold water at all times even while the water is flowing through to prevent sewer gas from escaping. One source of the odor, (if that's what your problem is), could be from a disposer if you have one. Running the water constantly is a MAJOR waste of water.
The floor drains trap may be dry. Floor drains rarely get used so the water in the trap can evaporate. The P trap essentially ``traps'' water in the trap seal which prevents sewer gas from emanating into your house. If this trap dries out, there is no barrier to stop the gas. Try pouring water down the floor drain.
Evaporation. In dry environments or in fixtures that are rarely used, water in the trap can simply evaporate. This is particularly common in vacation homes or seldom-used guest bathrooms.
There should always be water in the trap, that is the purpose of it. It's to hold water and prevent sewer smell from coming out of it.
The answer to this is “yes” and “no.” If your EZ trap filled with water, then you might have a problem. While your EZ Trap should have some water in it occasionally (it's there to help drain extra condensate, after all), a clog in your drainage system could lead to a backup or overflow of water.
Reasons why a P-trap loses water
There are a few factors that might cause the P-trap to have an insufficient amount of water: The water in the P-trap can evaporate due to excessively dry air conditions. Oscillation occurs when too much outside air enters the pipe, displacing the water out of the bowl.
Other than draining slowly or not at all, the smell in your shower will let you know if the P-trap needs cleaning. If your shower smells like sewage or has a foul odor, your P-trap is most likely not functioning properly.
This usually happens to a sink or appliance that hasn't been used in a long time. We generally see it in utility sinks or guest bathrooms. When the P-trap dries up there's no water and therefore, no seal. Simply run the water for 10-15 seconds to re-establish a seal and you should be good to go.
Make sure the top of the P-trap and the bottom of the sink's tailpipe are properly aligned, then tighten the slip-joint nut by hand and then with slip-joint pliers until you feel moderate resistance. Repeat the process where the end of the P-trap meets the drainpipe that disappears into the wall or floor.
Traps can lose their water from too much wind and the air outside of the house, which could be getting into the pipes and may bounce the water out of the bowl.
P traps are expected to have liquid ran through them at least every 14 days. However, field conditions such as drafts from a fan or furnace can accelerate the evaporation.
In most cases, a p-trap loses its water seal because it hasn't been used for a long time. Depending on the area, some p-traps can dry out in about three to five months if they don't experience any water use. Additionally, the p-trap may be leaking, or something may have drained the water in the p-trap.
Use the Fixture Regularly
Regular usage can prevent P-traps from drying out. Make it a habit to run water through infrequently used drains at least once a week.
If the P-trap is made of metal, inspect it for any signs of rust or deterioration—common issues that afflict older plumbing fittings. Should you encounter water leaks under the sink regularly, it likely means that the integrity of the P-trap has been compromised, necessitating immediate attention.
Running your sink obviously flushes water through the trap and down into the drain line. However, when you shut the faucet off, a small amount of water always remains inside the bend at the bottom of the P-trap. This water acts as a barrier that seals off the pipe so that the smelly sewer gases can't escape.
For standard P-trap repairs or replacements, where the P-trap is easily accessible and no significant complications are encountered, the cost can range from about $150 to $250. This includes the cost of a new P-trap and labor.
In some cases, an improperly installed p-trap can also lead to clogs. The p-trap is designed to trap debris and prevent it from entering your plumbing system, but if it's not installed correctly, debris can build up and cause a blockage.
If you don't have a plumbing wrench, adjustable pliers can also help. Once the nuts are loose, slide them away from the p-trap and pull the trap out. You'll most likely find a lot of gunk inside the trap. Remove this with your fingers or run water through the trap into the bucket to flush out the gunk and any clogs.
this is easy and basic, its most likely that your outlet pipe from the washer is too far in to the waste pipe and poss even beyond the U bend, pull it out a little and the trap will be able to fill with water again cutting off the smell.
You might be wondering: Should there be water in the trap shower? You might be surprised, but the answer is yes. Shower waste traps are designed in a way to always have a little water sitting in the shower tray in order to prevent any malodorous gasses from the sewer to enter your bathroom.
Strong sewer smells in your basement could indicate the lateral is blocked or broken, causing waste and sewage odors to back up into your basement. But that's the worst-case scenario. Sometimes, a neglected drain is the culprit, in which case a thorough cleaning can blast away odors.