Connect a Garden Hose Under A Sink: An Easy Guide

In some cases you might find that the most ideal water source is in your kitchen and you’d like to connect a garden hose under a sink. 

This could be the case anytime an outdoor water source is non-existent or in a less than ideal location. Maybe it’s in your garage or it’s a utility sink in your workshop.

Perhaps you live in a condo with no outdoor hose bib and would like to use a hose to water your balcony garden.

Or perhaps you live in a home with a water source far away from your watering needs.

You’ve likely found many tutorials that will teach you how to connect a hose to a sink faucet.   This is not ideal if you use your hose often, having to connect and disconnect  every time you need it.

We can solve this problem by adding new hose bib under your sink with a shut off valve. You can then store an expandable garden hose under your sink which will allow you to keep it connected without interrupting use of your sink’s faucet. 

What You Need to Connect a Garden Hose Under a Sink

Let’s look at the parts and tools needed as well as a step by step process to install a hose spigot below your kitchen sink. 

Tools & Parts Needed to Attach A Garden Hose Beneath a Sink

These hardware measurements in the list below apply to a water source with a 3/8″ threading, which is standard for most modern homes.  

If you think your plumbing is particularly old, you may want to take some measurements before you start.  Some older plumbing uses 1/2″ threading.  

Remember you’re measuring diameter of the inside of pipe tube where water will flow.  Watch this video if you need help measuring your pipe sizes.

You should be able to find most of these parts at your local hardware store.    The list contains links that connect you to pictures & pricing on Amazon.

* Important:  Before you buy all these materials, you should take a look at the space under your sink, and consider taking some measurements.  You may need to adjust slightly based on your needs.

For Instance, I listed a 20″ FIP hose, but you may not have enough space under your sink and need to buy a 10″ Hose.  

Additionally the wall mount I link to below might not work in your case.  In one of the videos below, he attaches the valve to an existing pipe using zip ties.  That works too!  

Here’s what you’ll need:

• One 3/8″ Three Way Compression Hose Adapter
• One 20″ long 1/2″ FIP Compression Hose
• One 1/2″ Steel Nipple
• One FIP 1/2″ Ball Valve
• One 1/2″ to 3/4″ Male Garden Hose Adapter
• Pipe Wall Mount
• A Good 3/4″ Expandable Garden Hose
• Adjustable Wrench
• Plumbers Tape (AKA Teflon Tape) 
• A Pail and Rag

A Note About Compression vs. Pipe Thread

The key thing to realize going into this – what most novices might not – is that we are moving from compression threading from the water supply to pipe threading that your garden hose will attach to.  

You cannot attach pipe threading to compression threading.   If you do, it will leak.  No matter how much teflon tape you apply.

This is why we need all the adapters & fittings listed above.  We’re not only adapting to size (3/8″ to 3/4″).  We’re moving from compression threading to pipe threading.

Step by Step Installation Instructions

Here’s what you’ll need to do to connect a garden hose under your sink.  I’ve also linked to some videos that help to explain.  

Note that these videos are teaching a different end goal, such as installing a dishwater line, etc.  Nevertheless, they will help you understand how to connect a garden hose tap beneath your sink.

This video is applicable until about 1:20 in:

Essentially what we’re doing is creating a second cold water line with a “T” shaped fitting.  We’ll then attach a valve to it so you can turn the second water source off without interrupting flow to your sink faucet. 

Let’s get started!

1. Place Pail Under You Sink’s Water Source

You’ll likely want to run cold water through your garden hose.  You’ll find that there are two water sources under your sink.  Cold water usually comes from the water source on the right.  Place your pail under that one to catch any leaking water already in the line.

2. Turn Water Source Valve to the Off Position

This is a good opportunity to test to make sure you are working with the cold water supply.  Try running cold water out of your faucet.  None should come out while the hot water still runs normally.

3. Use Your Wrench to Remove Existing water line From Water Source

The water line is usually a metal threaded hose leading from a valved water source to the base of your faucet.   Remove that hose from the water source, leaving the attachment to the faucet intact.

4. Tighten Three Way Compression Adapter to Water Source

The compression adapter should tighten securely onto the water source coming from the sink wall.  3/8″ is the standard size threading for most modern homes.

Apply 2 or 3 layers of teflon tape to male thread. Hand tighten, then tighten with a wrench another half turn.

5. Attach Faucet’s Cold Water Hose Line to Top of Compression Adapter

You’ll want to attach the hose to the compression adapter threading facing upward towards your sink.

Apply 2 or 3 layers of teflon tape to male thread.  Hand tighten, then tighten with a wrench another half turn.

6. Attach 20″ FIP Hose To Compression Adapter

There should be just one remaining threading open on the compression adapter.  Apply 2 or 3 layers of teflon tape to male thread.  Hand tighten, then tighten with a wrench another half turn

7. Attach 1/2″ Steel Nipple to Open Female Threading of The FIP Hose

Apply 2 or 3 layers of teflon tape to male thread.  Hand tighten, then tighten with a wrench another half turn

8. Attach 1/2″ Ball Valve to Steel Nipple

Apply 2 or 3 layers of teflon tape to male thread on the steel nipple.  Hand tighten, then tighten with a wrench another half turn

9. Attach 1/2″ to 3/4″ Male Hose Adapter

Apply 2 or 3 layers of teflon tape to male 1/2″ thread on the hose adapter.  Hand tighten to ball valve, then tighten another half turn with the wrench.

10. Move Ball Valve to the Off Position, Then Turn Water Supply Back On

Check for leaks and if you notice some, you can apply a little more teflon tape and/or tighten. 

11. Attach Pipe Wall Mount to Ball Valve and Mount

It’s important to mount your valve somewhere to prevent any weight hanging on your fittings. 

You don’t want any of your fittings loose or dangling. Over time this will deteriorate the threading and cause leaks.

In other words, you want to create an “S” shape in your FIP hose moving up above your water source or below.

Most sinks have a solid wood panel either near the floor of the sink cabinet or near the roof by the base of the faucet that will hold screws.  

Determine the best location for your shut off valve .   Be sure you have clearance to both turn the valve on an off and attach your garden hose easily.   Mount with the appropriate sized screws.

12. Attach Expandable Garden Hose To Male 3/4″ Threading

Apply teflon tape to threading and tighten by hand.

There are two reasons I’d suggest an expandable hose, which are illustrated in the video below.   1) No hose reel needed!  It will easily fit under your sink in a small bucket.  2) They self drain better than standard garden hoses, which will be less messy in an indoor setting.

A Helpful Video About Adding a Garden Hose Connection Under a Sink

What If I Connected My Hose and Now Have a Leak?

If you completed all the steps above and have a leak, it could be a number of things. Here are a few of the most likely culprits to double check:

1. You have mis-matched threading. Double check your connections and make sure that you have compression to compression and pipe to pipe threading. You may be missing an adapter somewhere.
2. Loose connections. It may just be a matter of tightening something properly. This is a hard to access area and can be hard to tighten everything properly. You may need to take a wrench to some connections to get the leverage you need to tighten adequately.
3. Not enough teflon tape. This stuff is gold when it comes to leaks. You can layer more around a threading than you think. If you notice a leak somewhere and there’s only a layer or two, try adding two or three more layers.
4. Leaks above the connections. Be sure to check for leak above where it looks like there’s a leak. There are a lot of curves and elbows in the piping under your sink. A leak up high that drips at an elbow below can make it seem like the leak is at the elbow. Use a paper towel to dry off your piping to discover where the leak actually is.

Conclusion

And there you have it.   I hope this helps you create a new water source below your sink for a garden hose attachment.

If you’re like me, you have a lot of indoor plants.  This creates an easier way to water them more often and save time.

Happy Watering!