When it rains, rainwater runoff has to go somewhere when it falls. Because of gravity, it will usually go to the lowest point it can, pouring into any available culvert or break in the tank. As the water collects, it takes up space, causing the gas to move upward to accommodate the increasing volume of water. That’s because the fumes have a lower density, so they’ll begin to come out of sewers and cause a bad smell in the process.
If you’re on a septic tank and notice a foul odor inside your home when it rains, the cause may be any — or a combination — of the following reasons:
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.
Cold temperatures can cause downdrafts from plumbing vent stacks. In this case, you will notice the odor varies during the day, especially if the weather is windy. If the odor tends to subside as temperatures go up, downdrafts are the most likely cause of that terrible sewer smell in your house.
If the septic tank is full, it can cause the pump to fail. As such, new wastewater will not come in to replace the old wastewater, producing a foul smell as a result.
A blocked venting system in the septic tank is another possible cause of a sewer smell in your house. This often happens if you’ve had work done on the home or to the landscaping, and the vents are no longer working properly. The result will be sewage gases that can’t escape from the wastewater, accumulating in your house instead and causing a foul smell.
For more information on septic tank inspection, contact Morse Engineering and Construction.