PVC – SDR 35

SDR (Standard Dimension Ratio) 35 is a PVC plastic pipe that is commonly used for modern sewer lines. SDR is a ratio of pipe diameter to wall thickness. SDR = D/s. SDR35 means that D (outside diameter of the pipe) is 35 times the thickness of the wall of the pipe.

SDR35 is thinner than Schedule 40 pipes. However, it is also more flexible which helps to prevent cracking underground when settling of the pipe occurs.

SDR35 has been an industry standard for sewer lines for the last approximately 35 years. This pipe is expected to have a 100 year minimum service life. Although, because production has not yet reached this age it cannot be confirmed.

*Interior view of SRD35 sewer line taken from NHI sewer inspection.