Abstract: An exhaust filter for insertion into an exhaust port of a liquid bath vacuum cleaner has an elongated, tubular inlet secured to a lower housing, which lower housing is secured within an upper housing. The upper end of the tubular inlet extends into the upper housing and is provided with a flat top portion and a series of openings between angled vanes so as to direct air flow entering the tubular inlet evenly around the circumference of the angle vanes and through a HEPA filter sealingly secured between the lower and upper housings. Air flows through the HEPA air filter and out slotted openings in opposed ends of the exhaust filter. The flow of air at one end passes by a rotary blade having an indicator element thereon, which indicates the condition of the HEPA filter, and when the exhaust filter must be replaced.