1 1/2 Inch Drain Not Cutting It? How to Upgrade Your Kitchen Sink to 2 Inches

If your kitchen sink seems to drain slowly or gurgle with standing water, the 1 1/2 inch drain pipe may be to blame. While this size is standard for residential kitchen sinks, it has limited capacity for heavy water flow. Upgrading to a 2 inch drain is an effective solution to improve drainage.

We’ll also cover how to determine if your sink needs more capacity, the benefits of upgrading, and a step-by-step guide to DIY installation.

When to Upgrade Your Kitchen Sink Drain to 2 Inches

A 1 1/2 inch drain line is suitable for a single regular sized kitchen sink in a home. But when you have a larger basin, double sinks, or several fixtures using one line, the 1 1/2 inch size can't always keep up.

Signs your existing kitchen drain line is undersized and needs an upgrade include:

• Water draining from the sink very slowly
• Gurgling sounds from the drain
• Standing water in the sink that is slow to drain
• Overflowing water when the sink is full

Some common causes of poor drainage with a 1 1/2 inch kitchen sink drain are:

• Heavy use of a large single basin sink
• Multiple sinks or appliances using one shared drain line
• Frequent use of a garbage disposal
• Buildup of gunk, grease, and clogs

Heavy Water Flow

The biggest reason a 1 1/2 inch drain line can't keep up is the amount of water flow. These drains can handle about 4-5 GPM of water. But larger sinks, double sinks, and additional fixtures can exceed this capacity.

For example, a garbage disposal boosts water flow substantially while grinding food waste. This is especially true for continuous feed models. If you already have borderline drain performance, a disposal can overload a 1 1/2 inch pipe.

Shared Drain Line

Using a single drain line for multiple sinks or appliances is another situation where capacity gets compromised. Even if each fixture has a 1 1/2 inch tailpiece, combining the flow can overload the shared pipe.

Island sinks with an overhead pot filler, prep sinks, or a nearby dishwasher can contribute to drainage issues when tied into the same line.

Benefits of Upgrading to a 2 Inch Kitchen Sink Drain

Switching to a 2 inch drain line has several advantages:

• It can handle around 9 GPM flow rate - 50% more than a 1 1/2 inch pipe.
• Accommodates high flow from multiple sinks and appliances on one line.
• Prevents backups from heavy water usage.
• Allows unrestricted drainage even with a garbage disposal.
• Reduces chances of clogging from food debris and grease buildup.

The extra capacity of a 2 inch drain provides a reliable solution for challenging kitchen drainage situations. It's a worthwhile upgrade if you're experiencing any signs of a undersized drain line.

Smooth Water Flow

A 2 inch pipe maintains a consistent water flow with less obstruction. This prevents the sluggish drainage you get with a smaller overloaded drain. Water enters the pipe with less resistance for a faster drain time.

Shared Drainage

If multiple sinks or appliances empty into one line, a 2 inch pipe accommodates the combined water flow. Bottle necks are avoided and each fixture can drain freely without affecting the others.

Clog Resistance

Larger drain lines are less prone to clogs from food particles, grease, and other debris. The wider diameter allows solids to pass through more freely. This minimizes sluggish drainage and the need for snaking your clogged sink.

Determining If You Need a 2 Inch Drain

Here are some ways to assess whether your kitchen requires an upgrade to a 2 inch drain line:

Evaluate Your Drainage Needs

Consider your kitchen's specific drainage requirements:

• The number and size of sinks
• Presence of a garbage disposal
• Any other fixtures (dishwasher, insta-hot tap) on the shared drain line

This gives you insight into the total drainage volume you need to handle.

When to Choose 2 Inch Drain

Some kitchen features indicate 2 inch drain line is best:

• A double bowl kitchen sink
• An extra-large single basin sink
• A garbage disposal unit
• More than one sink using the drain line
• A commercial style kitchen

These all involve higher water volumes that will benefit from a larger 2 inch drain size.

How to Install a 2 Inch Kitchen Sink Drain

Upgrading your kitchen sink drain line to 2 inches is a manageable DIY project. Here are the key steps involved:

Drain Line Sizing

First, check your existing drain line size and length. Measure from the sink trap to the main waste line connection. Account for any required code minimums or maximums.

Materials

You will need:

• 2 inch sink drain basket strainer and tailpiece
• 2 inch PVC or ABS plastic pipe and fittings
• Plumbers putty or silicone

Remove Old Drain

Disconnect the pipes, removing the old tailpiece, trap, and strainer assembly. Clean off old putty residue from the sink.

Install New Strainer

Apply fresh plumber's putty around the new 2 inch strainer. Insert it into the sink drain hole and tighten the mounting nut below the sink.

Assemble Drain Pipes

Connect the trap arm to the tailpiece, bending and cutting pipe as needed. Attach the trap and outlet pipe that connects to the existing waste line.

Test for Leaks

With the new 2 inch drain installed, run water through the sink and check all joints and connections for any leaks.

Cost Comparison of 1 1/2 vs 2 Inch Drain Installation

The parts for a 2 inch drain kit will cost more than a standard 1 1/2 inch assembly. However, upgrading your existing drain line will save money in the long run by preventing costly clogged drain repairs.

Parts Cost

Expect to pay around $25-50 more for a 2 inch sink drain kit. This covers the strainer, tailpiece, trap, and associated fittings.

DIY vs Hiring Plumber

This drain upgrade can generally be tackled as a DIY project, saving the expense of calling a plumber.

Prevents Repairs

Spending money upfront on a larger drain line saves you from far more expensive repairs later to clear clogs and backups.

Added Value

The benefits of better drainage make the modest additional cost of a 2 inch drain well worth it.

FAQ About Upgrading Kitchen Sink Drains

Is it Easy to Change the Drain Size?

Yes, the process involves disconnecting the old 1 1/2 inch drain pipes and installing new 2 inch components in their place. It can typically be done by a DIYer in one afternoon.

Can I Mix and Match Drain Sizes?

It's recommended to use all 2 inch drain pipes for a complete upgrade. But if needed, you can connect a 2 inch tailpiece to an existing 1 1/2 inch trap using a bushing connector.

How Difficult is Installing a 2 Inch Drain?

The installation process is very similar to a standard 1 1/2 inch drain. But working with larger 2 inch pipes may require an adjustable wrench for tightening fittings.

Will a 2 Inch Drain Work with My Existing Pipes?

In most cases yes, you can tie a new 2 inch tailpiece and trap into the existing kitchen sink drain line. Just confirm the size and length to the main waste line.

Do I Need to Hire a Plumber for This Drain Upgrade?

A skilled DIYer can typically install a new 2 inch sink drain without requiring a plumber. But if you are uncomfortable with plumbing, hiring a pro may be worth the cost.

Upgrading to a 2 inch drain line is an effective solution if your kitchen sink is showing signs of poor drainage. This provides the extra capacity needed for today's large sinks and garbage disposals.

Carefully assess your overall drainage requirements to determine if a 2 inch drain makes sense. Installation can be completed as a DIY project if you are comfortable with basic plumbing work.

Taking steps to prevent clogged and overflowing sinks is well worth the modest additional cost of a larger drain line. Investing in the right sized kitchen sink drain maximizes functionality and avoids headaches down the road.