Waste disposal units come with different sizes of motors. The size of the unit and its HP rating is often linked to family needs and size. As a rule of thumb, one would assume that the bigger the family the more waste is produced. A small family could manage with a ⅓ or ½ HP motor. A medium sized family of 6 a ½ to ¾ HP motor. A larger family would probably benefit from an HP rating of ¾ to 1 HP. The higher the HP rating will determine the noise produced. Thankfully, the unit is not in continuous use and only used in short bursts? Serviceteam Ltd. will install any InSinkerator of your choice, just call us and we will advise.