How to Figure Kitchen Sink Drain Line Slope

The angle at which your kitchen sink's drainage pipe slopes directly affects the efficiency of your kitchen plumbing system to process waste. If a pipe slopes too deeply, lighter waste material will flow too quickly to wash away heavier material. And if the drainage pipe's slope is too gentle, your kitchen's drainage will move too slowly. A slope of 1/4 of an inch is recommended for optimal drainage. If you suspect that your kitchen's drainage pipe doesn't have a suitable slope, you can figure out the slope of the pipe yourself before calling in professional maintenance.

Drop light
Pitch level
Box cutter (optional)

Instructions

- 1
  Set up a lamp or drop-light beneath your sink to illuminate your work space.
- 2
  Open the access panel beneath your sink to gain access to your sink's drainage line. If your sink doesn't include an access panel, you'll need to use a box cutter to open the sheetrock barrier and access your kitchen's plumbing.
- 3
  Locate the vertical drainage pipe. Follow the vertical drainage pipe to the diagonal "sweep" fitting that connects it to the horizontal building drain.
- 4
  Place your pitch level, or "plumber's level," against the drainage pipe, orient the level horizontally so that it parallels the pipe. Take note of the bubble inside of pitch level as it settles between the fractional interval on the level. The right side of the bubble indicates the fractional slope of your pipe.

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