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Installing a New Toilet Water Inlet Tube

How do I install a new intake line to my toilet?  What are my options to make the connection.

(If you haven't yet, click HERE to open the separate toilet graphics page.  You may need to refer to it.)

There are a number of circumstances where you may need to replace your toilet water inlet tube... replacing the toilet, replacing the flush inlet valve and replacing the tank-to-bowl seal are three examples.  OR JUST IF IT BEGINS TO LEAK AND TIGHTENING THE NUT DOESN'T WORK!

Types of Toilet Inlet Tubes 

The most common inlet tube at the time of this writing (and in my opinion the best looking)  is the chromed copper tube with flanged end and washer,(below left), so I'll use it as my installation example. A brief discussion of it's synthetic cousin, the polybutylene (plastic) tube,  and the braided stainless steel hose follow.

You can use plain old 3/8" copper tubing if you are especially cheap or don't care what the connection looks like. Look at the upper frame graphics. A special conical washer is used for a compression seal between the coupling nut and the inlet valve. Connections at the shutoff are the same.

Galvanized pipe is so uncommon, except in really ancient installations, as to warrant little comment. It is solid and unbending. If you need to replace it, do so with one of the other styles mentioned here, for future flexibility and ease of repair. Because the pipe is 1/2" rather than the standard 3/8" used in all the other connections, you will need to either get an adaptor to reduce the shutoff valve outlet to 3/8" compression, or replace the shutoff.

Polybutylene Plastic Toilet Inlet Tubing...

Another type of inlet tubing is the polybutylene (plastic) tube.


The wide or conical end attaches to the bottom of the inlet valve using the standard inlet valve coupling nut. These tubes are super easy to install, and can be cut with scissors, a sharp knife, or a standard tubing cutter.

Some plumbers are hesitant to install the plastic lines because they feel that they may fail in very high pressure or temperature situations. If your water is supplied from your own well, you should be able to use these with no problem. However, if you have water pressure over 90 pounds, or if your hot water temperature is over 160 degrees F, you should use one of the other options above, or a braided stainless steel supply tube.

There are only minor differences between the plastic tube and the copper tube installations, except for the fact that the plastic is more forgiving and flexible.

Braided Stainless Steel Supply Tube is the easiest of all to install... 

Our final entry into the Inlet Tube Hall of Fame is the braided stainless steel supply tube (below).  It is designed with screw-on connectors on both ends, making a very solid and simple connection at both the shutoff and the inlet valve.

It is extremely flexible and makes installation very easy. Because this type of supply tube cannot be shortened, you must make a fairly precise measurement of the length you need, and then go to the next larger size, just to have some of that old fashioned breathing room.


If you are unsure, buy a few different lengths, and return the unused ones to the store!

If you have too short a distance for the shortest available tube, buy a longer length and bend it into a loop!  OOPS, look like somebody ate the supply tube! Oh well, you get the idea! (P.S. Any snake charmers out there?)

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