Red Seal Plumbing Practice Exam

A 1.5 inches is too small for a residential clothes washer because it may cause clogging and slow draining. C: 2.5 inches is larger than necessary and can lead to wasted water and slower drainage times. D: 3 inches is unnecessary and may result in higher installation costs for the homeowner. Therefore, the most appropriate size for a residential clothes washer drain is 2 inches. This size provides efficient drainage without overspending on excess pipe size. Additionally, it is a common standard size used in most residential buildings.