When air is compressed a high amount of water can get into your air stream due to the water vapor in the compressed air stream condensing. The flow of water in your air lines can have a negative effect on downstream equipment like air tools.

Therefore, it is important to have a water separator installed in your compressed air system. This page will describe how to make a homemade air compressor water separator!

Table of Contents

How to Make a Water Separator for Air Compressors

First of all, ask yourself why you’re going through this effort when so many water separators are readily available, cheap and easy to install! Visit our Air Compressor Water Separators & Moisture Filters guide for the best that are available now.

If you really want to have a go at making your own water separator then let’s first take a look at what you need for the project.

What You’ll Need

Here is a list of everything you’ll need to have at hand before beginning and their quantity in brackets:

  • 3/4″ Copper 90 degree Elbow (10)
  • 3/4″ Copper pipe in 2-inch pieces (9)
  • 3/4″ Copper pipes (Type L) cut in 72″ height (6)
  • 1/2″ Threaded ball valves with female ends both sides (3)
  • 3/4″ – 1/2″ male adapters (3)
  • 3/4″ Copper Tee (3)
  • 2 1/2″ to 3/4″ Brass nipple (1)
  • 3/4″ Brass street elbow with male and female end (1)
  • 3/4″ Threaded male adapter (1)
  • 3/4″ Brass compression fitting for regulator (1)
  • 3/4″ Rapid air NPT filter regulator (1)
  • 3/4″ Compressed air hose (1)
  • 3/4″ Threaded brass ball valve with female ends both sides (1)
  • Teflon tape
  • Soldering flux
  • Solder strand
  • Propane torch

Note: it’s important to not use iron pipes as they corrode very fast and will affect the quality of the compressed air. Some alternatives you could use instead of copper are: galvanized steel, stainless steel or aluminium… but costs can be greater!

Step-by-Step Guide on How to Make a Water Separator

Now that you have everything at hand, let’s get into the method for a homemade air line water trap!

  1. First of all, start by joining 3 x 2″ copper pipes with a 90-degree copper elbow on each side. Ensure you apply a light layer of soldering flux inside the copper elbow and on the outside of the pipe before fitting them together to ensure the pipe doesn’t get oxidized when it is heated.
  2. Take another 3 x 2″ copper pipes and fix a copper tee on each of them then add the remaining copper elbows to the ends of every copper pipe. Make sure you add soldering flux again.
  3. You will have 3 x 2″ copper pipes remaining, take the joint with the copper tee and join each pipe. The second 2″ copper pipe should be joined to the copper tee.
  4. Using 5 of the copper pipes, attach the joint with the copper tee to two type L copper pipes. One of your joints should only be joined to a single long pipe, so you must ensure that you attach that one of the side with the copper elbow.
  5. Take the other joints and attach to the other side of the type L copper pipes whilst ensuring that there’ll be a continuous flow of air through the chambers. One of the joints will be attached to a single pipe.
  6. Solder the joints using the propane torch and solder to ensure that the pipes to not leak. To do so, heat the pipes on the joints and melt the solder on top when it is hot enough or when the flame on the side turns green.
  7. Fix the 3 male adapters (3/4″ – 1/2″) on each of the outlets at the bottom and solder them to avoid leaks.
  8. Add the threaded 1/2″ ball valves below the male adapters using some teflon tape.
  9. Cut the remaining 72″ copper pipe into halves and fix on each side of the set up/
  10. One side can be connected to the brass street elbow to go to your regulator while the other side attaches to your compressed air hose from your air compressor.

Now you should have a DIY water trap for air compressor!

Youtube Demonstrations

I have picked out some youtube demonstrations that may vary from the method I have provided you with, but will certainly be helpful to you!

They’re not the best examples on how to do it as they use too many valves. And worse still, using PVC pipe for your compressed air system isn’t recommended at all!!

FAQs (Frequently Asked Questions)

How do I keep water out of my air compressor?

To keep water out of your air compressor, you will need to implement air filters / separators that can filter out the moisture from the air stream. Another option is adding a dryer to the system in order to dry the air so that you have the highest quality available.

How does a water trap compressor work?

A water trap is a device attached to an air compressor which pulls the moisture out of the air before it is delivered to your air tools.

Does my air compressor need a water separator?

A water separator is a necessary and very beneficial addition to any air compressor to ensure that your air tools are protected from damage and receive the highest quality of air possible.

Where do you put the water separator on an air compressor?

Water separators should be around 30-50ft away from the compressor or as far as it can, so that the compressed air is able to cool down as much as possible before reaching the separator. This way, the filter will be able to catch more moisture from the air and provide better quality air to your tools.


If you have any questions regarding making your own water separator for air compressors, then please leave a comment below, with a photo if applicable, so that someone can help you!