An ostomy appliance comprising: a pouch wall defining at least a portion of a collection chamber configured to collect and store effluent from a stoma; an inlet formed in the pouch wall configured to be secured around the stoma; and a filter assembly comprising a filter, a valve and a bypass venting chamber extending between the filter and the valve, wherein the valve comprises: a closed configuration in which gas flow from the collection chamber to the bypass venting chamber through the valve is restricted; and an open configuration in which the collection chamber and the bypass venting chamber are in fluid communication with one another such that gas is received in the bypass venting chamber from the collection chamber through the valve, wherein the filter comprises an active gas inlet section configured to receive gas from the collection chamber; and a filter outlet section for exiting gas to the atmosphere; characterised in comprising a bypass gas inlet section configured to receive gas from the bypass venting chamber, wherein gas enters the bypass venting chamber from the collection chamber through the valve in the open configuration; and in that the filter assembly is configured to allow gas from the collection chamber to flow toward the filter through the active gas inlet section in an active venting state with the valve in the closed configuration, and wherein when the active gas inlet section becomes occluded, actuating the valve transitions the valve from the closed configuration to the open configuration allowing gas from the collection chamber to flow toward the filter through the bypass gas inlet section. a pouch wall defining at least a portion of a collection chamber configured to collect and store effluent from a stoma; an inlet formed in the pouch wall configured to be secured around the stoma; and a filter assembly comprising a filter, a valve and a bypass venting chamber extending between the filter and the valve, wherein the valve comprises: a closed configuration in which gas flow from the collection chamber to the bypass venting chamber through the valve is restricted; and an open configuration in which the collection chamber and the bypass venting chamber are in fluid communication with one another such that gas is received in the bypass venting chamber from the collection chamber through the valve, a closed configuration in which gas flow from the collection chamber to the bypass venting chamber through the valve is restricted; and an open configuration in which the collection chamber and the bypass venting chamber are in fluid communication with one another such that gas is received in the bypass venting chamber from the collection chamber through the valve, wherein the filter comprises an active gas inlet section configured to receive gas from the collection chamber; and a filter outlet section for exiting gas to the atmosphere; characterised in comprising a bypass gas inlet section configured to receive gas from the bypass venting chamber, wherein gas enters the bypass venting chamber from the collection chamber through the valve in the open configuration; and in that the filter assembly is configured to allow gas from the collection chamber to flow toward the filter through the active gas inlet section in an active venting state with the valve in the closed configuration, and wherein when the active gas inlet section becomes occluded, actuating the valve transitions the valve from the closed configuration to the open configuration allowing gas from the collection chamber to flow toward the filter through the bypass gas inlet section.