A Drain Smell That Comes and Goes

The smell is not there when the plumber can come, and it is there when you are cooking dinner. Intermittent sewer odors feel haunted. They usually have a rhythm. Unused traps dry out and then get a splash and go quiet. A bath fan or a dryer pulls hard and tugs at a weak seal. Wind on the plumbing vent changes the day. You will not see the rhythm if you only complain. You will see it if you write the time and what was running.

For a week, note the smell in five words. Time, room, rotten or musty, which fans were on, whether you were home all day. Patterns fall out. "Guest bath, mornings, nobody used the shower" is a dry trap. "Kitchen, when the dryer runs" is a pull problem worth telling a plumber. "Only after the wind storms" is a vent conversation, also a plumber, not a candle.

Do the refill anyway, even before the week is over, at every rarely used fixture and floor drain. If the intermittent smell was a trap that was almost dry, the week goes quiet and you learned something. If it continues on the same cue, you have a better note than "sometimes it smells."

Musty that comes and goes with rain or with the air conditioner is a different intermittent. Do not call it sewer unless it is the rotten drain note. Rain smell is moisture. AC startup smell is the system. A house can have both in one month. The notebook keeps them from becoming one expensive theory.

Do not answer an intermittent smell with a standing chemical treatment in the drain. You will be away when it happens, and the chemical will not explain the cue. Water and a note are enough until a person who does pipes needs the note.

If the smell is gas, even once, leave and call the gas utility from outside. Intermittent gas is not a puzzle to log from the kitchen. Sewer you can log. Gas you do not study.

When you call a plumber, read the log. The worst visit is "it smells sometimes" with no room and no cue. The useful visit is "guest tub, every Monday until we run the water" or "kitchen, only with the dryer." You are allowed to know more than the person on the phone, because you live there.

Keep the log where you will actually write. A note on the fridge beats a perfect app you will not open while holding a laundry basket. Five words. You can stop when the pattern repeats twice. You do not need a month of data to refill a guest tub.

If the cue is a fan, leave that fan off for one evening as a test, if you can do it without creating another problem. Smell or no smell. One off-cycle is information. Then turn it back on and call with the result. Do not leave bath steam unvented for a week just to prove a point.

Musty days and rotten days should be different lines in the log. If you only write smell, you will mix a dry trap with a wet sill and buy the wrong help. Two words, rotten or musty, are the whole upgrade. Use them even when you are annoyed.

If the log stays blank because the smell never shows up during the week you promised to watch, extend it. Intermittent means inconvenient. The day it returns, write the line before you light a candle. That single line is the week.

This is a house check, not a diagnosis. Symptoms go to a doctor, and big wet repairs go to a licensed pro.

Smell logs are the kind of plain step in When Your House Doesn't Feel Right. It is $2.99 at https://clearnestair.com/book.