of carafe 14 has an angled top to create an annular head gas space 62 in which the off gas may accumulate during the treatment of water in carafe 14 ozone is bubbled through the water by means of sparger 38 the off gases accumulate above the water e g above fill line 60 in head gas space 62 ozone may cause side effects in people exposed to sufficient quantities of these gases e g headaches accordingly the off gases are preferably collected and treated e g by exposing them to a destructor which will convert the gas to a more benign form for example in the case of ozone the destructor may be a catalyst for converting ozone to oxygen such as one or more of manganese dioxide titanium dioxide iron oxide and carbon contact between ozone and one or more of these catalysts will case the ozone to convert to oxygen which may then be released harmlessly from the system accordingly in one preferred embodiment carafe 14 includes a gas conduit having a first end in fluid flow communication with head gas space 62 and a second end which is connected in fluid flow communication with an off gas treatment member e g a destructor when carafe 14 is placed on base 12 and apparatus 10 is actuated to treat water in carafe 14 referring to fig3 carafe 14 is provided with a support rod 64 having two arms 66 each arm 66 has an upper end 68 positioned in head gas space 62.