This phenomenon is shown in the famous movie "Gasland" which proved that it had no connection to unconventional gas extraction. The fire caused by the presence of biogenic methane in water was not the result of exploration activities. The problem was connected with the methane deposits located near a water intake but the Pennsylvania authorities warned house owners of the need to safely ventilate methane from their wells long before the development of the Marcellus deposit. Abiding by the laws in force which in Europe are much more restrictive than in the USA and proper care of the environment by extraction companies may completely eliminate the risk of penetrating the gas into drinking water.