AirGradient Forum

Could sewer gas increase CO2 and TVOCs?

#1

My unit has been operating well, thank you. I do shut my WiFi off overnight so there are some gaps in the data.

For the past 5-6 months I’ve noticed an increase in CO2 and TVOCs. I’ve pasted the CO2 week chart below. ChatGPT says there is some correlation. Both values drop when a door and window are opened.

I changed both the gas furnace filter and fresh air ventilation filter on Sept 4. I will take the AirGradient outside today to let it recalibrate. I have a couple of situations that might be contributing, including a powder room that has been left demo’d for a few years (toilet reinstalled - unused - flushed occasionally, sink drain covered in plastic), a first floor laundry drain that has an odor when the washing machine is used, the washing machine door that is left open to let it dry after a wash, and there may be other sources…

Nothing has really changed over the past year so this may be difficult to track down. From what I read best approach may be to let the sensor calibrate, then move it from one room to another, I guess on the same day when the reading is high, to try to narrow down the source. First I might just open things to get good readings, then close and see how long it takes to increase.

Am I correct to include sewer gas as a possible source? Am I on the right track generally?

TIA.

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#2

Opened everything up for a time, then closed. The readings rose steadily:

1:00 pm 762 156
1:34 835 179
2:43 932 194 opened again
3:27 874 144

Then later I realized I have been leaving the washer detergent tray and door open to let it dry between washes. I closed them, we’ll see if that makes a difference.

#3

I could see TVOC maybe increasing with a sewer drain open, but I wouldn’t expect CO2.

In what room is your sensor located? I see regular increases in CO2 on the sensor in my bedroom where we sleep in a room with a closed door. Once the door is opened and people are moving around, it decreases in that room. If the house becomes vacant mid-day that would also contribute to CO2 levels decreasing even more.

#4

The sensor is in the living room on my desk. I sleep with the bedroom door closed.

#5

Well… it may be related to the washer, but in a different way.

The drain hose went into 1-1/2" PVC pipe with the top otherwise open. There was gurgling whenever the pump was on. I read that modern HE washers pump more water out faster, along with more air, and so can empty the P trap causing sewer gas to waft up the pipe and into the room. There are a couple of different styles of stoppers that can mitigate this, I tried a gray silicone one and did a load of sheets, seems to work ok. Right now I am sitting here with the A/C on, nothing open for about 3 hours, and CO2 is 690, VOCs 90.

#6

This is super interesting because I have the exact same problem with my HE washer and it’s been driving me nuts. Please post up the stopper that you’re using to fix this!

1 Like
#7

On the large online shopping site, B0CT5BJ56C

But read my review “Thin and flimsy…” for how NOT to install it.

Another source could be the dishwasher and/or sink disposer. In the process of using the item below to scrub the inside of the disposer, it seems debris may have been pushed into the dishwasher, the water in the sump never drains completely and so… another source. After taking it apart and doing my best to clean it, it no longer drains. Sigh.

B08HCJJRSN

#8

We are in a moderate drought here, late September, Northeast USA, a few leaves on the ground, my home is about 100 ft from a bog and stream that is almost dry. Light rain overnight. I opened the window and it was not “fresh” smelling air. I left it open for about 20 minutes then closed it.

CO2 1006, VOCs 123 about 3 hours later.