What Is the Size of PVC Pipe Used for Kitchen Sink Drains?

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Kitchen sinks require a certain size drainpipe.

When installing a new kitchen sink drain or repairing an old leaking one, you need a particular size drainpipe. This pipe is the standard size for all kitchen sinks. It provides the right amount of flow to drain a kitchen sink during heavy use. Since all kitchens use this size of pipe, it is best to stick with it during any repair. This reduces the chance of problems matching pipes down the road.


Kitchen Drain Parts

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The kitchen drain is divided into several parts, each with a distinct purpose. The first part is the drain basket. This is a two-piece part fitted into the sink basin drain hole. It contains a bowl that sits on top of the sink drain hole, a threaded piece of pipe, washer and lock nut. The lock nut and washer secure the drain on the sink. The drainpipe connects to the threaded portion of pipe on the drain below the sink basin. This is the part that concerns you when you replace a drain. T

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Kitchen Drainpipe Connection

The kitchen drainpipe connects to the drain under the sink. The drain has a threaded pipe sticking out below the lock nut that secures the drain to the sink basin itself. The drainpipe threads onto this pipe with a connector. Since the pipe is 1 1/2 inch in diameter, kitchen drainpipes are also 1 1/2 inches in diameter. To connect the drainpipe, use a solid metal or brass connector on the end of a piece of PVC drainpipe. Thread and tighten the connection to secure the drainpipe.


P-Trap Design and Sizing

The next part to concern yourself with is the P-trap. This is the P-shaped plumbing fixture connected to the drainpipe. It is made of two U-shaped PVC fittings, one with a longer end than the other. The fittings also measure 1 1/2 inches and connect directly to the drainpipe. As this is still technically part of the drain, it is important to keep all pipe sizes the same. This uniformity ensures the drain flows properly and prevents clogs.


Drain Line Pipes

The next section of the drain is the pipe connecting the P-trap to the main drainage pipe. This pipe is usually 1 1/2 inches in diameter. However, many homes have 2-inch drainage pipes. If this is the case, you need a reducing bushing to connect the pipes together. A 1 1/2 inch to 2 inch reducing bushing is the right choice here. Secure the 1 1/2 inch end to the kitchen drainpipe and the 2 inch diameter end to the home's main drainpipe.


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