Sink Drain Pipe Size Code

Below our tables 1 and 2 summarize common plumbing code specifications for fixture venting and vent pipe sizes and distances that a plumbing fixture can be located horizontally from the vent stack.

Sink drain pipe size code.

Bathroom vanity with cooper sink. All the pipes that connect to the tailpiece including the p trap assembly. For instance the minimum pipe diameter for a washing machine drain is pipe with a 1 1 2 inch diameter. Compare the fixture to the minimum sizes of drainage pipe by fixture table.

The last size is 4 inch drain pipe that can be connected to 160 units in horizontal stack and 240 units in vertical stack. Some older sinks may have drains that connect to a 1 1 4 inch tailpiece but most modern drains have a 1 1 2 inch outlet. Horizontal drain pipes connecting the sink drains to the trap must have a minimum slope of 1 4 inch per foot toward the trap. You ll see these distances also in our sketch at left.

This is the minimum size to use for building sewer or drain pipe that is connected to the toilet. Tables of plumbing drain pipe vent pipe sizes critical distances to plumbing fixtures. A single trap can service more than one sink but adjacent drains cannot be farther apart than 30 inches. This pipe size is commonly used for sanitary drainage.