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Installing A Toilet Seat On A One-Piece Toilet

Learn how to use our hardware kits to install a new toilet seat on your 1-piece toilet that uses anchors

Many one-piece (low boy) toilets use special toilet seat mounting anchors to secure the toilet seat to the bowl. Since the tank is directly connected to and essentially part of the bowl it may be difficult if not impossible to reach through the tank to tighten the toilet seat bolts. Here we will show and explain how to attach your Bemis toilet seat with Easy•Clean & Change Hinges to a one-piece toilet that uses anchors to secure the toilet seat. Please note the HK36 kits are not needed with the Affinity 200E3 or 1200E3 seats because the hardware included with those seats will work with the #84999 anchor kits.

Tools needed: Adjustable wrench and phillips head screwdriver

For Kohler (and possibly "will fit" American Standard, Eljer, or Universal Rundle) - If the anchors have been removed or are missing, then you will also need a #84999 Anchor Kit. You can purchase a #84999 anchor kit here = $47.07 +


For Toto - If the anchors have been removed or are missing, then you will also need a #THU651N Top Mounting Seat Hardware Kit. You can purchase a hardware kit here.

Step 1:

Make sure anchors are installed into the bolt holes of the bowl. If anchors are missing then install the anchor kit. Once installed the anchors are wedged against the inside of the porcelain holes. For Toto kits, you will simply need to push the rubber anchors into the holes in the top of the bowl, then skip to Step 6.

Step 2:

Anchor kits include a bolt, a lock washer and a regular flat washer to set the anchors in place. Only one set of each is included because it is used for both anchors and once the anchors are set, the bolt, lock washer and flat washer are discarded.


Step 3:

If you need to install anchors, use the tool that comes with the anchor kit to hold the anchors from slipping.


Step 4:

Put the flat washer on the bolt and then the lock washer. Place the bolt into the anchor and begin to hand tighten the bolt clockwise.

Step 5:

Using an adjustable wrench, continue to tighten the bolt in a clockwise motion until the bolt is snug onto the top of the anchor tool. Once the bolt is snug, use the wrench and un-tighten and remove the bolt, flat washer and lock washer using a counter clockwise motion. Repeat this step for the other anchor. Once completed, the anchors should now be firmly secured inside the bolt holes. The bolt, flat washer and lock washer will not be used any further. Discard or put into your bolt collection.


Step 6:

If you are installing the Bemis toilet seat with Easy•Clean & Change Hinges you will now use this HK36 hardware kit (shown in the picture below) to complete the seat mounting. The mounting posts/bolts and long nuts kit included with the Bemis seat will NOT be used. The HK36 hardware kit is identical in size to the posts/bolts provided in the toilet seat mounting kit, which will not be used. Additionally, if you are using the Toto seat hardware kit, you will use the bolts provided in that kit and NOT the bolts included with the HK36 kit.

You can purchase the HK36 Hardware Kit for 1-pc Toilets here = $5.19 +

Step 7:

Do NOT use the mounting posts/bolts and long nuts mounting kit that is included with the Bemis seat. These are not needed when using the HK36 mounting kit. These bolts/mounting posts and long nuts are used for normal installations to toilets with easy access to the bolt from the underside of the bowl.

Step 8:

Install the HK36 hardware kit. Put one of the bolts with the phillips head through the quick-change mounting post and slide the bolt into one of the two anchors. Tighten clockwise by hand until it becomes too hard to further tighten by hand. The bolt with the phillips head is the same size bolt as the "setting" bolt as shown in Step 2.

Step 9:

Use a screwdriver and continue to tighten the bolts until the quick-change post is snug against the porcelain. Be careful to not over tighten.

Step 10:

Follow Step 8 and Step 9 and install the other quick-change mounting post into the other anchor. Once they are both snugly installed, the top of the bowl should look like the picture shown below.

Step 11:

You are now ready to attach the seat. Standing in front and facing the toilet move the locking hinges on the toilet seat to the left. Gently push both hinges on to the quick-change mounting posts until the bottom of the hinge is touching the porcelain.

Step 12:

Now, simply move the locking hinges back to the right and the hinge will lock onto the quick-change post, securing the seat. Pat yourself on the back and admire your handy work.


Please note: The method presented here for installing these seats may not be suitable for every model of one-piece toilet. If you are unsure if a particular kit will work for you, please contact us prior to ordering.


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Please note the information provided here is intended to give a basic knowledge of plumbing related repairs. This information is general, and may not suit all applications. If you are at all unsure of your abilities to complete one of these projects, please consult a professional. Always check with local code regulations and the proper authorities before beginning a project.



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