Red Seal Plumbing Practice Exam

What size drain is typically installed for a residential clothes washer?

1. 1.5 inches

2. 2 inches

3. 2.5 inches

4. 3 inches

The correct answer is: 2 inches

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.