Kitchen Sink Drain Size

Kitchen Sink Drain Size

A standard kitchen drain is 3 1/2 inches in diameter. This is the measurement across the center of the drain, from one side to another. The drain strainer, the bowl-shaped piece inside the drain mouth, matches this dimension. It is designed to sit inside the drain mount and seal it closed when flush to the drain bowl. All kitchen sinks have a drain this size to make installations easier. The drain connects to a pipe with a 1 1/2-inch diameter.
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Kitchen Sink Drain Size

A bathroom sink has a much smaller drain size. Since it is only used to wash hands, shave and brush teeth, there is no need for a larger drain hole. Bathroom sink drains are 1 3/4 inches in diameter — half as large as the kitchen sink drain. After installing new bathroom faucets, the drain is usually replaced. So, it makes sense to standardize the drain size. That way bathroom faucet manufacturers can provide the right-sized drain with their faucet. The drains have a 1 1/4-inch tail pipe.
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Kitchen Sink Drain Size

A bar sink drain is slightly larger than a bathroom drain, but smaller than a kitchen drain. It handles more heavy-duty usage than bathroom sinks but not as much use as the kitchen sink. Bar drains are 2 inches in diameter. They connect to either a 1 1/4-inch or 1-1/2 inch tail pipe. These drains, like bathroom and kitchen drains, use a P-trap, which is a J-shaped pipe that connects to the main drain line.
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Kitchen Sink Drain Size

Most drains perform one function: to drain off water from the sink. In order to accomplish this and to make changing drains easier, sink drain sizes are standardized. Different types of drains, in different areas of the home, have different sizes. In virtually all cases, the drain size suits the function of the drain.
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Kitchen Sink Drain Size

Learn how to replace the P-trap underneath your bathroom or kitchen sink The curved pieces of drain pipe underneath your sink, commonly referred to as p-traps, do a lot of dirty work. Over time they leak, become corroded or get plugged with years of accumulated soap and grease. When replacing a P-trap, you should use the same type of trap you remove. Traps are made from ABS (black), PVC (white) or brass (either chrome-plated or natural colored). Traps come in 1 1/4 inch (standard bathroom sink) or 1 1/2 inch (standard kitchen sink) inside diameter sizes. Be sure to check so you get the right size replacement at your local store. In this guide we’ll show you how to replace a P-trap in a few easy-to-follow steps.
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Kitchen Sink Drain Size

In the most basic system, the sink drain opens to a vertical length of pipe, called the tailpiece, which connects to the P-trap assembly that consists of a curved pipe and a horizontal extension that extends to the waste line. Things get more complicated when more than one sink, a dishwasher or a garbage disposal is connected to the drain system, and there may be extra drain extensions, tees and Y-fittings.
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Kitchen Sink Drain Size

The curved pieces of drain pipe underneath your sink, commonly referred to as p-traps, do a lot of dirty work. Over time they leak, become corroded or get plugged with years of accumulated soap and grease. When replacing a P-trap, you should use the same type of trap you remove. Traps are made from ABS (black), PVC (white) or brass (either chrome-plated or natural colored). Traps come in 1 1/4 inch (standard bathroom sink) or 1 1/2 inch (standard kitchen sink) inside diameter sizes. Be sure to check so you get the right size replacement at your local store. In this guide we’ll show you how to replace a P-trap in a few easy-to-follow steps.
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Kitchen Sink Drain Size

Attach the trap arm to the drain stub-out, using a slip nut and washer. Remember to keep the beveled side of the washer facing the threaded drain stub-out. If necessary, the trap arm can be cut to fit with a hacksaw.
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Washing machine frequently use the same drain as the kitchen sink, especially when they are a combination fixture. If they are in combination, use 2″ pipe; if not, 1 1/2″ pipe will probably work successfully.
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This fixture serves a variety of purposes such as dish washing, cleaning of food, rinsing out articles of clothing, and several others. As a result, waste water discharges vary in composition, and the pipes drawing off this waste must be prepared to handle maximum drainage problems. A I 1/2″-diameter waste pipe is considered to be the minimum size to use for a kitchen sink, but common practice is to allow a margin of safety by using 2″ pipe. The nature of the wastes from this fixture also makes the need for adequate cleanouts apparent.
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One of the suggestions is to use an AAV (Air Admittance Valve). I was definitely considering this originally, but I had assumed that even an AAV should be at least 6″ above the sink, but if it can sit underneath the sink then going that way would be a lot simpler. – irrational John Aug 22 ’15 at 19:28
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Fixtures must not be placed too close together. This is critical in a bathroom, where space may be at a premium. Determine the correct pipe sizes for drains, vents, and supply lines. Determine the correct pipe materials. Most inspectors will accept rigid copper pipe for supply lines and PVC for drain lines. To ensure adequate water pressure, you may need to replace an existing globe shutoff valve with a full-bore ball or gate valve that does not impede the flow of water. If pressure is low, you may need a booster pump. Where pressure is too high, you may need a pressure-reducing valve. The installation of plumbing must not weaken the structure of a house. The inspector may require that you reinforce joists that have been cut to accommodate pipes. Other requirements include the use of fire caulking around pipes and placement of protective plates over pipes.
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List fittings in detail on your plan so you will be sure to purchase the right ones. Be sure to use special drain fittings, such as a closet bend, so wastewater can flow smoothly. Inspectors will have specific fitting requirements for different fixtures.
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When water empties from the kitchen sink, it goes through a sometimes complex network of pipes before it gets to the main waste pipe, which is typically in the wall. This pipe network is usually made of PVC and can be 1 1/4 or 1 1/2 inches in diameter.
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Pipe Size 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. All the pipes that connect to the tailpiece, including the P-trap assembly and all the horizontal extensions, are either 1 1/4 or 1 1/2 inches in diameter. Wider pipes are preferred because they accommodate faster water flow, and you can switch from the narrower to the wider pipe in the middle of the network by using an adapter. You also need an adapter at the wall, where the pipe diameter usually changes to 2 inches.