Methane gas odors are toxic to humans. Septic systems, cesspools, drywells all generate harmful methane gasses that if exposed to humans can cause asphyxiation and cause infection to the human body. In the event you believe methane gas exist, evacuate the area immediately and contact your plumber and authorities immediately for a further evaluation and risk assessment of the area.
Old out dated septic tanks that have been abandon or replaced can harbor methane gas and should be removed. Unused septic systems can cave in presenting a hazard to unsuspecting family members and pets. These systems when walked over can cave in creating a serious hazard and have been known to cause death in some cases.
Whenever you’re moving into a new home, visit your local courthouse and research the septic and sewage records. Determine if you have a septic tank or connected to city sewer.