What Size Supply Line Is Needed For A Kitchen Faucet?

As a piece connecting the intake and the discharge port of the kitchen faucet, the supply line needs to bear a standard length and diameter. So, what size supply line is needed for a kitchen faucet?

Let’s find the information related to this aspect is available in the first section of this instruction.

What Size Supply Line Is Needed For A Kitchen Faucet?

What Size Supply Line Is Needed For A Kitchen Faucet?

The galvanized steel, PEX, or copper pipes of a household system for water supply normally consist of two main parts with different measurements. 

One is the main pipe which ensures the main water supply gets its diameter of 3/4 inches. And the other – branch line is to feed every single fixture with the size of 1/2 inch in diameter. 

As for the latter, this 1/2-inch pipe comes to the terminal to the sink when you close the water valve. Also, it is one of the deciding factors which help to determine the size for connection of the hose.  

Another highlight is that the inlet and the pipe must be a right match. For details, the inlet could be a 1/2-inch FPT standing for female pipe threat in the case of galvanized pipes. Alternatively, we suggest a 1/2-inch sweat connector for the copper-made pipes. Or a barbed connector measured ½ inches will not be a bad idea for the PEX pipes.

Does Size Really Matter With Standard Faucet Supply Lines? 

Yes, it does really matter. With a line, there is no need for a diameter that gets bigger than 1/2 inches. In other words, this standard measurement is good enough for a sufficient water flow and pressure for your household’s daily needs. 

Basic Supply Line Piping Under The Sink 

A water supply system underneath the sink often includes two important lines. They are a combination of cold and hot feeds. 

Put simply, the cold feed on the right is commonly the soft copper line which features a shutoff valve. By contrast, the left position is for the hot feed and another valve to lock the water flow when in need. Besides, the second line tends to extend slightly further to a connector piece called the bit.

From that bit, the line can get the right fit and run-up to the kitchen faucet easily. In addition, this part consists of a compression nut along with a rubber washer. Both of them do the function of sealing the joint of connection. 

Replacing Supply Lines For Your Kitchen Faucet 

It is necessary to replace the lines of the faucet every 5 years. This periodic replacement ensures effective protection against numerous possible leaks. However, when it comes to braided lines with higher durability, the frequency can be every 10 years. 

The replacing process is relatively simple with several steps as below. 

  • Step 1: Gather all tools in need (a pair of adjustable wrenches).
  • Step 2: Seal the connecting joints with the rubber washer. The step will be much easier with a supply line featuring both compression and locking nuts. 
  • Step 3: Turn the line off and then open the handle of the faucet.
  • Step 4: Loosen two nuts mentioned above and remove them. 
  • Step 5: Connect new supply lines to the feed and use the wrenches to hold the pipe. 
  • Step 6: Turn the handle off to ensure that every connection gets tight. 

Related: How to connect 2 supply lines

What size is a standard kitchen faucet? 

In terms of the kitchen faucet sizes, you should base on the sink types. Let’s divide them into three categories including the sink with insufficient headroom, the deep sink, and the shallow sink. 

A sink with insufficient headroom is suitable to match with a short faucet. If you install a tall one, the setup will look extremely weird and maybe so out of place. Honestly, the beautiful look cannot be a good solution if the faucet is wrong to fit. 

A deep sink often requires a short faucet. This combination helps to maximize the precision and prevent water from splashing. 

A shallow one seems to be the most versatile option. In particular, it can work well with both tall and short kitchen faucets. 

Regardless of the three types of faucets above, there is still a standard range for the size. Generally speaking, the kitchen faucet often measures around 8 inches. 

What size water pipes are required for the kitchen sink? 

As for some old sinks, they commonly feature drains connecting to a 1.25-inch tailpiece. On the other hand, various current modern models come with an outlet measuring 1.5 inches. 

It does not matter how the drain is, the tailpiece connection requires a P-trap along with the horizontal extension. This assembly typically is from 1.25 to 1.5 inches in diameter. 

In general, we suggest choosing wide pipes for the faster flow of water. For the narrower pipe, you can switch it to a wider size with an adapter. 

How do you measure a faucet hose fitting? 

Here is the process.

  • Step 1: Prepare a measuring tape and the hose.
  • Step 2: Measure the inner circle of the hose to know about its diameter. 

How do I connect two supply lines to a faucet? 

There are 6 simple steps in total.

  • Step 1: Turn off the water flow and prepare gears in need such as safety gloves and goggles along with a bucket.
  • Step 2: Drain the lines into the bucket.
  • Step 3: Determine the hot and cold line.
  • Step 4: Use Teflon Tape to wrap the faucet’s end before installation. Then, screw that end and connect it with a compression fitting to the supply line.
  • Step 5: For the lines made of copper or hard plastic, position and then bend the pipes. Insert the fittings and connect it to the compression fittings.
  • Step 6: Turn the supply back on to check whether there is any leak.

Do faucets come with supply lines? 

On the market currently, some kitchen faucets are available with the factory-attached supply lines made of soft copper. In particular, you can find these pieces for both cold and feed. It means that the lines connect directly to shut-off valves. 

However, you should pre-shape the lines before placing the sink into its position. This step helps to correctly measure the distance from the water supplies and the tubes. 


So, what size supply line is needed for a kitchen faucet

The common measurement ranges from 3/4 to 1/2 inches. Based on different types of faucets, we can choose the appropriate size. Hopefully, all the information mentioned above can help your consideration. Especially with the instruction for replacement, feel free to drop us a line if you need more support.

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Edvian Berrios is a homeowner who has become a plumbing expert through self-study and practical experience. Despite not being a professional plumber, Berrios's deep understanding of fixtures and do-it-yourself techniques has enabled him to successfully handle even the most challenging plumbing problems in his own homes.