How to Install a Kohler Highline Toilet


Installing a new toilet can seem like a daunting task, but with the right preparations and step-by-step process, it can be straightforward. The Kohler Highline is a popular two-piece toilet known for its classic, elegant style and reliable flushing performance. With some basic DIY skills and tools, you can have your new Highline toilet installed in no time.

In this comprehensive guide, we will walk through everything you need to know to successfully install a Kohler Highline toilet, from removing the old toilet, preparing the bathroom, connecting the water supply, and installing the new toilet. We will cover proper safety precautions, necessary tools and materials, steps for removal and installation, troubleshooting tips, and care and maintenance recommendations. With these detailed instructions, you can install your Highline toilet with confidence.

Overview of the Kohler Highline Toilet

Before we get into the installation process, let’s briefly overview the Kohler Highline toilet line. Here are some key features and specifications:

  • Two-piece design with separate tank and bowl.
  • Available in round and elongated bowl shapes to fit bathrooms of all sizes.
  • Offered in a range of heights from standard to comfort height.
  • Uses 1.6 gallons per flush (GPF), meeting EPA WaterSense standards for high efficiency.
  • Flush valve design provides reliable siphoning action to clear waste.
  • Made of vitreous china with durable enamel finish to prevent staining.
  • ADA compliant models meet accessibility guidelines.
  • Covered by a one-year limited warranty.

The Highline collection includes several different models featuring these core characteristics to suit different bathroom needs and styles. For this installation guide, the steps will be applicable to any standard two-piece Highline model.

Preparing for Installation

Before you start removing your old toilet, there are a few important steps to take to prepare for a smooth installation process. Proper preparation will make the installation much easier and minimize the risk of leaks or other issues down the line.

Gather Supplies and Tools

You will need the following supplies and tools on hand for installing the Kohler Highline toilet:

  • Kohler Highline toilet (tank and bowl)
  • Wax toilet ring/wax seal
  • Toilet mounting bolts and plastic washers
  • Toilet seat nuts and bolts (if not included with toilet)
  • Flexible toilet supply line
  • Adjustable wrench
  • Channel lock pliers
  • Teflon tape
  • Hacksaw (if cutting supply line)
  • Caulk and caulk gun
  • Sponge/rags
  • Flashlight
  • Gloves
  • Safety glasses

Turn Off Water Supply

Locate the water supply valve that feeds water to the toilet and turn it clockwise to shut off the water. This valve is usually on the wall behind the toilet or located on the wall under the tank.

Tip: Flush the toilet once the water is off to empty the tank and ensure the valve is closed.

Disconnect and Remove Old Toilet

Start by unscrewing the flexible supply line from the toilet tank and closing the shut-off valve. Flush any remaining water from the tank.

Use a sponge to soak up any excess water in the bowl. Use a bucket or towels to catch any water that may spill out when removing the toilet.

Unscrew the nuts and bolts holding the toilet to the floor. You may need to pry them loose with a screwdriver.

Lift the toilet off the bolts and set it aside, being careful not to crack the toilet. Place a towel under the toilet base to prevent scratches.

Prepare Bathroom Floor

With the old toilet removed, inspect the floor around the toilet flange (the pipes that stick up from the floor). Look for any cracks or damage that need to be repaired. The floor surface should be level and securely supported.

Scrape off the old wax ring completely and make sure the bolts sticking up from the flange are anchored firmly. Replace bolts if needed. Apply caulk around the base of the flange if there are any gaps between the floor and flange.

Wipe the floor dry and clean using a rag. Apply painter’s tape around the perimeter of the flange to protect the floor from caulk drips later.

Connecting the Toilet Water Supply Line

Once the bathroom is prepped, it’s time to connect the new toilet’s water supply. Properly installing the supply line ensures your Kohler Highline toilet will have the water pressure needed to flush and fill the tank.

Install Shutoff Valve

If you are replacing the existing supply line, start by shutting off the main water supply to the bathroom. Flush the toilet to empty water from the tank and bowl.

Unscrew the old supply linenut from the valve and remove the line. Install the new shutoff valve according to the manufacturer’s instructions. Apply Teflon tape to the valve threads and tighten securely.

Connect Flexible Supply Line

Take the new flexible supply line and apply Teflon tape to the threaded ends. Connect one end to the shutoff valve at the wall. Tighten gently using pliers.

Connect the other supply line end to the bottom of the new toilet’s tank, where the water line enters. Hand tighten and then give an extra 1/4 turn with pliers.

Tip: Leave the shutoff valve closed for now while you install the toilet. You will open it to test for leaks after completing the installation.

Installing the Toilet

With the water supply ready, it’s time to mount the toilet on the flange. Take care to position the toilet correctly and securely fasten it to the floor.

Position Toilet on Flange

Set the new wax ring down over the floor bolts and around the flange, pressing to adhere it in place. The tapered cone should face up.

Carefully set the toilet bowl onto the flange, centered over the wax ring. The bowl outlet must align with the flange for a secure seal.

Caution: Lifting the bowl once seated can pull the wax ring out of place. If needed, remove toilet and reposition the wax ring before resetting.

Bolt Toilet to Floor

With the bowl centered, insert the washers and mounting nuts onto the flange bolts from below. Hand tighten the nuts fully, alternating between sides to keep the toilet level.

Finish by tightening with a wrench or pliers, being careful not to crack the porcelain. The mounting nuts should be snug but not over-tightened.

Install Toilet Tank

With the bowl tightened down, you can prepare the tank for mounting on the bowl. Insert the tank-to-bowl gasket into the opening on the bottom of the tank. Apply a bead of caulk around the top of the bowl where the tank will sit.

Lower the tank onto the bowl so the gasket and bolt holes align. Insert the tank bolts through the holes and hand tighten the nuts from below to secure. Finish tightening with a wrench, being careful not to crack the tank.

Tip: Don’t over tighten or you can crack the tank. The gasket only needs to be snug to create a seal.

Connect Water Supply

With the tank attached, reconnect the water supply line to the tank fill valve. Hand tighten and finish with a 1/4 turn of pliers.

Keep the shutoff valve closed and do not turn on the water yet. We still need to seal the base and check for leaks.

Finishing Touches

The final steps will complete the toilet installation and get your bathroom functional again. Take time with these finishing touches for long-lasting results.

Apply Caulk

With the tank and bowl securely mounted, wipe away any excess caulk or debris left from installation. Apply a smooth, continuous bead of caulk around the base of the toilet where it meets the floor. This seals any gaps and prevents leaks.

Install Toilet Seat

Sit the toilet seat on the bowl and insert the plastic washers and nuts from below. Tighten by hand, then give an extra 1/4 turn with pliers to snug the seat down. Don’t over-tighten or you may crack the seat.

Turn on Water and Test for Leaks

Open the water supply shutoff valve all the way. Let the tank fill completely and flush a few times to clear any air from the lines.

Spray the toilet fittings and connections with a light mist of water and check carefully for any drips or leaks. If leaks are detected, tighten connections as needed. Leaks at the base may require re-setting the bowl on a new wax seal.

Once no leaks are found, install all the toilet tank components like flapper, handle, lid, etc.

Final Cleanup

Remove the painter’s tape from around the base of the toilet. Apply silicone caulk where the toilet meets the floor for a seamless seal.

Wipe down the entire toilet to remove any dirt and dust. Clean any tools and tidy up the bathroom. Install any final touches like a toilet paper holder.

Congratulations, your new Kohler Highline toilet is installed!

Troubleshooting Common Toilet Installation Issues

While unusual with proper installation, a few problems can come up when installing a new Kohler Highline toilet. Here are some common issues and how to fix them:

Toilet is loose or rocks:

  • Tighten the mounting nuts below the bowl if loose.
  • Ensure the wax ring is sealed fully around the flange.
  • The floor support around the flange may need reinforcement.

Toilet leaks:

  • Check for cracks in tank or bowl. Apply caulk if minor cracks.
  • Bolts may be loose and need tightening.
  • Wax ring did not create proper seal – reset toilet on new wax ring.

Toilet won’t flush properly:

  • Make sure water supply valve is fully open.
  • Flush valve chain may need adjusting.
  • Clogged passages – use plunger to clear obstructions.

Water keeps running:

  • Flapper seal is worn and not sealing tank – replace flapper.
  • Improperly adjusted float – bend float rod to adjust water level.

Low water level in tank/bowl:

  • Partially clogged valve – clean fill valve assembly.
  • Supply valve not fully opened – turn water supply on all the way.

If problems persist after troubleshooting, contact Kohler support for additional assistance.

Caring for Your Kohler Highline Toilet

Your new toilet will function better for longer with proper care and maintenance:

  • Clean the bowl regularly using a toilet cleaner and brush to prevent stains.
  • Prevent hard water buildup in the tank with products designed to keep toilet components scale-free.
  • Avoid harsh abrasives, bleaches or chemical cleaners that can fade color or damage the vitreous china.
  • Check supply connections and valves periodically for any leaks needing tightening.
  • Monitor the flapper seal and replace when worn for a complete flush.
  • Keep all gaskets and seals lubricated with non-petroleum grease when replacing.
  • Tighten mounting nuts and tank bolts if the toilet becomes loose.

With regular cleaning and maintenance, your Kohler Highline toilet will operate smoothly for years. Call a plumber for any repairs needed outside standard maintenance.

Frequently Asked Questions About Installing Kohler Highline Toilets

Here are answers to some common questions about installing Kohler Highline toilets:

Is the Kohler Highline toilet easy to install?

Yes, the two-piece Highline toilet uses a standard installation process that is straightforward for DIYers with basic plumbing skills and tools. The key is taking adequate time to prepare and following instructions.

Does the toilet come with a toilet seat?

Most Kohler Highline models do not include the toilet seat. You will need to purchase one designed to fit the Highline bowl shape and size.

What toilet seat height is most comfortable?

Look for a comfort height model between 16-19 inches high for ideal accessibility. Standard height is around 15 inches. Measure rough-in to get the right bowl size.

How do I know which Highline toilet to get?

Choose based on bowl shape, rough-in measurement, height, flush performance, water usage, colors, and features like Quiet-Close seat. Get a chair height model for comfort and ADA compliance.

What is the best wax ring to use?

Use a wax ring designed for 3-4 inch floor flanges. Wax rings with plastic funnels adapt to varied flange heights. Choose wax over foam for best leak protection.

How long does it take to install this toilet?

With proper preparation, the full process takes 2-5 hours for first-timers. Experienced DIYers can install in 1-2 hours. Having an extra set of hands helps speed up the process.

What can I do if my toilet installation isn’t level?

Use plastic shims under the bowl base to level it out before tightening nuts. You may need to adjust the flange extension height or use a thicker wax ring.


Installing a new Kohler Highline toilet takes careful preparation, step-by-step installation, and finishing touches to get a secure, leak-free fit. Following this detailed DIY guide, you can upgrade your bathroom with a stylish, efficient Highline toilet. Take precautions, work slowly, double check your work, and don’t be afraid to call a professional if needed. With some patience and the right techniques, you can have your new toilet installed in no time. Here’s to successfully installing your Kohler Highline toilet for years of dependable performance!