Are septic tank gases dangerous?
Septic systems that use a leach field or other subsurface disposal methods produce biogas, mostly methane and carbon dioxide, as the organic matter decomposes. The gas collects in the septic tank, and some of it escapes from the plumbing vents. Therefore, a standard septic system should have a pipe running from the top of the septic tank to midway between the ground surface and grade level.
The other end of this vertical pipe should terminate in an open-ended “vent stack” that extends through the roof to ensure that any free-standing gas can escape before it enters your home. In many older homes, however, only one end of this vent stack may be connected to anything; often, there is no vent stack at all.
Households without any venting system are said to have a “foul air” or “closed” septic system. While this doesn’t pose the same type of explosion risk as an unvented gas furnace, it can still result in high concentrations of carbon monoxide inside your home. As a result, most states now require new construction with full-vented systems; existing homes may also need to be retrofitted with proper venting.
Unvented (closed) septic tank systems pose potential health risks because they produce large amounts of explosive methane/natural gas and carbon dioxide gases that can be dangerous if not properly vented outside the house. Although it is possible for natural gas appliances such as stoves, water heaters, and furnaces to backdraft (that is, draw dangerous gases into the house through the chimney or other air intakes), it is unlikely for this situation to occur unless there has been inadequate maintenance on the appliances.
The biggest concern is carbon dioxide. It can build up in a dwelling because CO2 is not flammable; therefore, there are detectors designed to warn occupants of dangerously high levels. An added danger with this type of system is that people or pets can asphyxiate from low oxygen levels without realizing their true condition – an effect known as “after drop.” After drop occurs when blood absorbs too much carbon dioxide during periods of low oxygen intake, such as heavy work or exercise.
Although methane is flammable, unvented septic system gas poses a much lower risk than natural gas from a well-maintained conventional gas-fueled furnace. Methane can asphyxiate an individual in concentrations of 16 percent to 60 percent.
Can septic tank gases explode?
Because methane is combustible, many people assume that gases from septic tanks can explode. However, this isn’t the case unless the tanks are vented improperly. Methane gas has a high flammability point of 5 to 15 percent in air.
This means that there must be at least five percent methane mixed with 95 percent air for methane to ignite. The same goes for natural gas, which is mostly methane and ignites more easily than most other fuels because it is lighter than air and diffuses rapidly away from its source.
Methane produced by anaerobic bacteria doesn’t explode but forms trace amounts of natural gas after about 12 days. It’s possible to use biogas as fuel or recycle it into energy. Septic tanks are not designed to store gasses, so when the tank is full, it simply covers up the wastes with additional sludge or grit.
Without ventilation, gases produced in a septic tank have nowhere to go and become lethal. For example, methane gas has an odor that smells like wet hay because one of its components is hydrogen sulfide which produces sulfur’s distinct smell at very low concentrations. The National Institute for Occupational Safety and Health set this threshold level at about ten parts per million. However, they recommend staying away from all decomposing organic matter even if there is no odor present.
As far as safety goes, it’s much safer to have a trained professional clean out septic tanks rather than attempt doing it yourself. A poorly maintained tank may result in an overflowing toilet which presents health risks all its own.
Can septic tank gas make you sick?
If your home or business has a septic system for sewage, then it should also have a leach field to disperse the liquid waste into the surrounding soil as well as an effluent filter (baffle) to trap large particles. The wastewater eventually makes its way out of the septic tank and through perforations in the drain-field pipes, dispersing into the surrounding dirt.
While this works fine for getting rid of what ultimately becomes groundwater pollution, it can sometimes become very smelly and produce noxious odors that waft up from under your yard. This is often due to one of three causes:
1) A lack of oxygen below the tank’s intake has meant that anaerobic bacteria have started multiplying, causing the tank to emit hydrogen sulfide gas.
2) A recent addition of an inspection chamber in the septic field has introduced air into the wastewater stream, possibly stirring up nastiness that was previously undisturbed for years or even decades.
3) The effluent filter (baffle) needs cleaning, and this allows soil gases / light crude oil / “sewer gas” to escape upwards through it instead of being carried away downwards through perforations in the drain-field pipes.
Is any of this dangerous? It can be if you breathe enough of the stuff – hydrogen sulfide is toxic because it attacks your central nervous system at its most fundamental level.
So can septic tank gas make you sick? Yes, it’s possible – but only if one or more of the above conditions is present and you’re constantly exposed to an overwhelming number of these fumes for a long enough period that your body just refuses to take any more and gives up altogether. There aren’t many documented cases of people dying from hydrogen sulfide poisoning during normal septic system usage, though.
What does septic tank gas smell like?
One of the most common questions people ask when they smell gas is, “What does septic tank gas smell like?” This question is easy to answer. Septic tank gas is usually hydrogen sulfide, which smells like rotten eggs.
Hydrogen sulfide comes from the anaerobic digestive process of bacteria breaking down the material in a septic tank or pit latrine and creating a stench that can be difficult to get rid of without professional help.
A septic tank is an underground watertight container for storing sewage. The overflow from a septic tank goes into a drain field, which is a series of pipes full of gravel and perforated with lots of small holes that lead away from the tank to prevent any excess build-up of water or sewage from entering the surrounding soil. In homes where there is a septic system, a professional can pump out waste from your septic tank every three to five years.
Some people report smells like rotten eggs in their home when they think their septic tanks may be backing up or leaking. This smell typically comes from hydrogen sulfide gas created by a bacterial breakdown in the septic system, but it may also come from sulfur compounds in the water itself.
Although hydrogen sulfide is usually harmless, it can be dangerous in high concentrations. In addition, some researchers believe that chronic exposure to low levels of this gas could contribute to health problems like fatigue and headaches. Call a professional plumber if you think your septic system may be leaking or backed up but do not know how to check for these issues yourself.