This 3/4 IN dual check valve repair kit prevents the reverse flow of polluted water from entering into the drinking water supply at the service entrance or at individual outlets. It consists of first and second check modules, 2 modules O-rings, union seal and check seal. It is designed for non-health hazard residential water system containment, continuous pressure applications. It is installed immediately downstream of the residential water meter, in a vertical or horizontal position. Check with local inspection authorities for installation requirements.