Carbon Monoxide from the shower?

The location of my smoke/CO alarm happens to outside my bathroom door. The last week or so, when I finish my shower or more often while I’m still in it, the alarm is going off. I don’t take very hot showers and I leave the door open and a window cracked, so it’s not like there is a plume of steam that billows out. The mirror doesn’t even fog. It occurred to me today that the alarm is also for CO and I thought maybe it’s something coming out of the shower head or water itself? I have to check with my landlady if we have gas heat for the water. Does this theory even make sense?

It might make sense…you may have an inefficient or inappropriately vented water heater. It kicks on when you take a shower in order to heat new cold water in the tank, and the CO level kicks up enough to activate the alarm. I would definitely investigate which alarm is sounding, and ask the landlord to have the water heater serviced/inspected if it is in fact the CO alarm.

If there isn’t a gas or oil water heater it could just be the steam causing some shorting in the detector. If could be defective. Have it checked out, don’t guess with a CO monitor.

the CO detectors wear out, the sensing element deteriorates, at about 7 years. as it ages there might be false triggering near the end of its life.

a combination alarm could also false trigger due to dust and moisture.

higher quality combo alarms will indicate the cause of the alarm.

How would CO from the heater enter the shower water?

Carbon monoxide is soluble in water, less so in hot water.
If there was CO in the cold supply (shouldn’t be though), the heater could be forcing it out of solution.

It wouldn’t, it would be in the air. It could be located right under the bathroom and improperly vented. Or it might be vented right outside the bathroom window or another window nearby.

to test if that might be the case then run a large volume of hot water at some other location (like the kitchen sink).

You haven’t been eating a lot of beans lately have you?

Even if the mirror does not fog up, there’s likely enough fine mist droplets to set off the detector. It could be false alarms.

The bathroom is off the kitchen, and where I wash dishes in the kitchen sink (with hot water) is also close to the alarm. This does not seem to trigger anything.

It might if you ran 20 gallons of hot water out.

It’s possible in theory, but seems very unlikely that there would be much CO in the water to begin with. A properly operating detector has to be able to distinquish between dangerous amounts and air pollution or small amounts generated by smokers or cooking. However, the situation still needs to be checked, may be there’s something weird going on at the local pumping station. But the simple first check is a different detector, and moving it out of the way of the steam.

i was replying to what i believe was your suggestion that CO in the air came from the hot water heater (if it was gas) putting CO into the bathroom environment.

the OP doesn’t know about the water heater (gas or electric).

i think that an aging CO detector might be giving false alarms.

a combination detector will trigger with high moisture.

i would ask the landlord to replace the detector if near 7 or more years old. if not replaced then have it verified wit another detector, it would make sense to me that a landlord would have a detector with a numerical readout for just that purpose.