How to Install Double Kitchen Sink Plumbing


Double kitchen sink plumbing is a simple and cost-effective way to add extra storage and counter space in your kitchen, while also improving drainage and air circulation. Dishwashing is easily done with a double basin. You can wash your dirty cooking utensils in one part and rinse in the other part.

Using a double kitchen sink makes garbage disposal easier. If one side is filled with dirty plates, you can use the other side for waste disposal. With a double kitchen sink, you can cook conveniently while maintaining good hygiene. So if you’re planning on upgrading your kitchen sink or installing a new one altogether, definitely take a look at double kitchen sink plumbing options.

Installing a double kitchen sink plumbing is not complicated. Just you need to follow all the instructions to avoid problems like leaks, slow drains, bad smells, or inflated water bills. With the right tools, guidance, and patience, you can install double sink plumbing successfully.

Double kitchen sink plumbing kits:

Snappy Trap 1 1/2″ All-In-One-Drain Kit for Double Bowl Kitchen Sinks.

OHIO SUPPLY Double Basin Simple Drain-Flexible Rubber Trap and Connectors For 2-Bowl Standard or Disposal Sink Drains.

How to Install Double Kitchen Sink Plumbing

8 Steps to Install Double Kitchen Sink Plumbing:

Gather All the Necessary Tools and Materials

Here are the materials and tools required:

  • Washers
  • Brand new double sink
  • Compression nuts
  • PVC Pipe
  • Sanitary Tee
  • Kitchen drain trap kit
  • Plumber’s Puffy (or Teflon tape)  
  • Silicone sealant
  • Pilers
  • Measuring Tape
  • Safety glasses
  • Hacksaw
  • Screwdriver
  • Pipe wrench
  • Markers
  • Puffy Knife

Before starting any plumbing activity, you need all the necessary tools. If you don’t have all the tools, you can buy or rent them from a nearby home improvement shop.

Since kitchen sink kits have different types and sizes, consult the store attendant to confirm that you are buying the right tools.

You can get plastic or metallic compression fittings, but most plumbers prefer plastic fittings because it doesn’t corrode and is easier to use. You can get a double bowl kitchen sink drain kit if you desire.

Turn off the Water Valve

Before beginning a double sink drain to one drain installation, you need to turn off the water valve. The water valve is found below the sink. If you can’t find it, you must turn it off from your house’s primary water supply line.

Mount Drain Assembly

You have to mount the drain assembly. It comprises flange and popup (also known as the stopper), the key body beneath the sink, and the ball-and-roll system that regulates the stopper’s movement.

Prior to fixing the sink in the cabinet, you have to mount the drain assembly in the wall opening at the bottom of any of the sinks.

You still have to install the garbage disposal system in the other wall opening. Apply the plumbers puffy to make each hole leakproof. You should tighten the screws with a plier.

Mount the Double Bowl Sink

Fit the sink into the cabinet. Clips usually come with sinks. Use a screwdriver to drive the clips into the cabinet.

Install the Garbage Disposal

The next step is to install a garbage disposal. Installing garbage disposal may seem complicated, but you can look it up from your manufacturer’s manual.

Additionally, you will find the steps to install double sink plumbing with garbage disposal comprehensively covered later in this article.

Mount the Tail Section

You need to fix the tail section now without the disposal system. Use a slip nut to connect the tapped outlet.

The slip nut is a gentle threaded ring that can be attached by hand. While installing it, you need to be careful.

Link Sanitary Tee to the Tailpiece

It would help if you used a plastic compression nut to connect the sanitary tee to the tailpiece. You can adjust the compression with your hands.

To determine if the tailpiece is firmly attached to the tee, insert a compression washer.

Measure the distance between the tea outlet and the disposal system with a measuring tape. Next, use a hacksaw to cut a piece of pipe, as the length, to connect the tee and the disposal system.

To ensure airtight connection on either end, don’t forget to use compression nuts and washers. Try to be careful when cutting the pipes.

Fit the P-Trap

Double sink p trap installation is not complex. Before wrapping up the process, insert the p-trap assembly into the lower edge of the p-trap.

Next, fit the p-trap to the drain inlet on the wall. Cover the p-trap with an adapter to prevent leaks.

How to Install Double Kitchen Sink Plumbing with Garbage Disposal

To plumb a garbage disposal with a double sink P trap, you may require the following material:

  • A garbage disposal unit
  • Hammer
  • A putty knife (plastic one)
  • Wire nuts
  • An old rag (or piece of cloth)
  • Plumber’s putty
  • Slip-joint pliers
  • Screwdriver
  • Non-contact voltage tester
  • Wire strippers
  • Utility knife

Step 1: Clean the kitchen cabinet beneath the sink

The kitchen cabinet needs to be clean, so you can easily work on it.

Step 2: Turn off the circuit breaker

Take a look at the circuit breaker wired to the disposal system, and turn it off. Before proceeding, ensure that there is no electricity passing through the wiring. Use the voltage tester to confirm.

Step 3: Detech the couplers that connect the extension pipe of the drain and p-trap

Take slip pliers to perform this operation. Next, keep these drain parts in a safe place. Insert a piece of cloth in the drain to stop a foul smell from polluting your kitchen.

Step 4: Unscrew the nuts beneath the drain coupling

Use your pliers to do this. When it’s loose enough, remove it by pushing it up. Separate the flange of the drain from the lower part of the sink.

Step 5: Scrape

Scrape off some puffy residue on the drain hole. Use the scraping knife.

Step 6: Apply puffy

Apply a good amount of puffy around the flange of the garbage disposal unit.

Step 7: Insert the flange

Insert the flange in the correct hole in the sink. Use the mounting ring to put it in place.

Step 8: Tighten the disposal unit

Tighten any screws using a screwdriver. Finally, you’ve installed your garbage disposal unit.

How to Install Double Kitchen Sink Plumbing with Garbage Disposal

Double Kitchen Sink Plumbing Diagram

Double Kitchen Sink Plumbing Diagram
Double Kitchen Sink Plumbing Diagram

3 Benefits of Double Sink to One Drain Installation

A double sink or divided sink has two bowls that are separated by a divider, offering more variety and space efficiency. Here are the benefits:

Managing Counter Space

Counter space is the extra space of a sink used for drying and storing appliances. The double sink has two individual bowls. You can use one of them for washing dishes and the other one for drying them. This saves more counter space for your other needs. You can also use a drying rack on one side.

More Choice of Configurations

Double sinks are available in various size configurations. So, it gives you more choices over how you want to utilize the sink. You can have both equal bowls or one bigger than the other. This also offers more innovative counter space layouts and aesthetic choices for your kitchen.

Save Detergent and Water

As you’re typically using only one side for washing, that individual unit is smaller than a single sink unit. So, you can have more water depth without spending too much water. This also saves the usage of detergent. It’s easier and more efficient to wash the dishes in this setup.

Do you need special plumbing for a double kitchen sink?

The double kitchen sink doesn’t require much special plumbing. They just need some extra components and add more complexity to the design.

For example, you need an elbow and a wye on the first drain to direct it towards the second one. You also need a tee to join the two drains and get a single drain out of them. Lastly, you need a p-trap after the tee, which is a common component among single and double sinks.

The assembly has more leakage opportunities, so you’ll need to be more careful. But the layout isn’t too complex to call a plumber.

Does a Double Sink Need Two Drains?

Initially, 2 drains come out of each sink of a double sink. But the final system has a single drain that goes out. There’s usually no need to take two individual drains to the end, unless you have complex pipelines, one pipe too much longer than the other, and so on.

Usually, the two sinks connect and share a single p-trap that goes to the final drain. Thus, they create a T-shape. Setting up two drains can ensure a long time before cleaning, but adds unnecessary cost and complexity. That’s why plumbers connect both into one.

Can a Double Kitchen Sink Share the Same Drain?

Yes, they can. It’s often a better choice. You can use the same drain of a double sink by joining the outlets with tee fittings. Following with a single p-trap, your setup is good to go. You can have a lower flow rate if you’re using both sinks together, but the setup is cleaner and simpler.

However, you may need individual vent depending on what type of surrounding environment and layout you’re using. If you face issues with draining even though everything is clean, vents might be the issue. You can check out the system with the help of professionals.

Does a Double Kitchen Sink Need a Vent?

Vents release pressure and prevent vacuum formation. Vacuum can significantly decrease or block drainage. Having a vent in a double kitchen sink setup is not mandatory but it’s recommended. Without a vent, weird smells can produce due to inefficient waste drainage.

This factor depends on your surrounding drainage environment like soil level. It can be difficult to figure out the necessity of a vent yourself. But having one surely helps. You can use an admittance valve that can allow or block air into the pipes. In cases of drainage issues, you can turn it on or off to troubleshoot.

Conclusion

Double kitchen sink plumbing is a great way to save space and increase your kitchen’s functionality. By installing a double kitchen sink plumbing, you can easily accommodate two standard kitchen sinks in the same space. Not only does this make your kitchen more organized and convenient, but it also reduces the amount of time you spend cleaning up spills and messes. When you install a double kitchen sink plumbing, be sure to follow all the instructions carefully to avoid any problems.

Lisa Burks

Hi, I'm Lisa Burks, founder of the Sink Formula blog, and plumber of 5 years experience.

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