The present invention discloses a method for self-cleaning filters without having to open the filter housing. Wash nozzles are integrated with the filter housings such that when the filters are clogged, both back-wash and regular washing can be performed with practically no down time. Moreover, without opening the filter housing, the hazardous components of the fluid to be filtered can be contained and dealt with before they escape the filter housing, thereby significantly reduces the environmental impact and harm to the working crew.