Installing a TOTO Washlet on a Skirted Toilet

Installing a TOTO washlet onto a skirted toilet may seem a little confusing and a bit difficult at first, but we here at can assure you that this isn't the case. Pairing a skirted toilet with a TOTO washlet is a great option many people opt for, but before you pull the trigger and purchase a TOTO washlet for your skirted toilet, you’ll want to make sure you meet the fitment requirements and possess the appropriate hardware parts. 

Let’s break down the details.

What is a skirted toilet?

A skirted toilet is different from a regular toilet. A skirted toilet has a smooth skirt design that conceals the trapway at the base, as well as the fill valve under the tank giving the toilet an elegant look. This design makes the toilet easier to clean and gives it a nice modern appearance. Although the design is great to look at, it does present a few issues for installing a TOTO washlet.

The process for installing a TOTO washlet onto a skirted toilet is a bit different than with a regular bidet seat. Below, we will discuss the possible issues and solutions for installing a TOTO Washlet.

What are the problems with a skirted design? 

1) The Fill Valve is Concealed

A typical 2 piece residential toilet will have its fill valve located underneath the toilet tank and easily accessible. TOTO bidets come with a 7/8” t-valve that connects directly to the fill valve under the tank for its water supply. Skirted toilets tend to have the fill valve concealed behind the toilet, thus making it inaccessible. There is often very little space between the back of the toilet and the wall. For a bidet seat, the fill valve area is crucial because this is where you connect your t-valve (or water splitter) that supplies your bidet.

2) The Underside of the Bowl is Inaccessible 

Normally, skirted toilets would present an issue when installing a bidet. This is because the underside of the bowl is inaccessible so typical nut and bolt style mounting hardware won’t work.

Luckily, this isn’t an issue with TOTO Washlets.  Toto Washlets come with their own top mounting bolts which will allow you to install your bidet onto a skirted toilet without issue. 

What are the solutions to these skirted toilet issues? 

1) Alternative T-Valve for Skirted Toilets + THP3141

The easiest solution to the fill valve issue is an alternative t-valve that can be installed on your shut-off valve instead of at your toilet's fill valve. This alternative t-valve is known as a t-valve for skirted toilets. This t-valve has top male and bottom female connections that are 3/8" compression threads, making it a perfect fit for most shut-off valves. The skirted t-valve has a standard ½” threaded outlet that leads to the bidet seat. This is the standard size for electronic bidet seat supply hoses, but TOTO Washlets have a proprietary hose connection and as such, require an adapter to be paired with the t-valve for skirted toilets.

This adapter is known as the THP3141 and will be necessary to successfully connect a TOTO washlet hose to a standard ½” threading. 

skirted t with adapter

2) Extension Hose for Skirted Toilets 

Another solution to the fill valve problem is an extension hose for skirted toilets that connects to the fill valve of your skirted toilet and extends the 7/8" connection. The extension will allow you to connect the original TOTO Washlet t-valve to the end of the hose, instead of to the fill valve directly. 

To install, you would disconnect your existing supply hose from underneath the tank and install this hose instead. The TOTO Washlet’s 7/8" t-valve will connect to the other end of this extension hose, and your existing supply hose will connect to the bottom of the t-valve.

You can also use TOTO’s fill valve extension part (9au321-a) which will add an additional 3 inches of length to the fill valve. However, it is important to note that installation these extension parts can be difficult if your toilet is already installed. This is due to the inaccessibility and difficulty of reaching the fill valve underneath the tank.