Methane in drinking water is non-toxic; however, it can cause spurting from taps and "water hammer" (i.e. sudden pipe vibration that occurs when a water valve is closed). Furthermore, if it is allowed to accumulate in enclosed spaces, it can cause oxygen deficient atmospheres, flammable conditions and explosions.
There is no Canadian drinking water quality guideline (Health Canada, 2012) for dissolved methane.
However, the Ontario drinking water standards (OMOE, 2003) provide an aesthetic objective for methane of 3 L/m3.
The US Department of the Interior, Office of Surface Mining recommends the following action levels for dissolved methane:
- <10mg/L - no action required other than periodic monitoring;
- 10 mg/L - 28 mg/L - well owners should consider removing potential ignition sources from the immediate area;
- >28mg/L - take immediate action to reduce methane levels.