For many decades, we relied on galvanized steel or copper pipe to distribute hot and cold water around our homes.
But more recently, PEX piping (also called cross-linked polyethylene piping ) has become increasingly popular, particularly amongst DIY’ers and those starting new construction jobs.
One of the biggest benefits of pex piping is the fact it’s incredibly flexible.
And as an added bonus, it also had convenient color-coding to help differentiate between cold and hot water.
But we often have to purchase pex piping in pre-coiled units, which can be tough to bend straight.
So today, we’re going to show you how to correctly straighten pex piping out without damaging it.
How to Straighten Pex Pipe: Step-by-step guide
You might ask yourself if you have to go to all this effort just to straighten the pex piping out, what makes it better than steel or copper pipe?
Now depending on where you intend to use it and the shape of your home, you will need to manually manipulate the pex pipe into the desired shape you’d like.
This can sometimes be an issue as pex tubing is generally shipped as a big coil to save space.
Pex piping tends to have a good ‘memory’ and likes to return to its original form.
This makes it difficult when you need long lines of straight piping in your home.
Fortunately, we have a bunch of fairly easy methods to help coax the pex tube into the shape we need.
1. Run Hot Water Through the Pipe
This is a great way to help straighten out a pex tube, as it doesn’t get water everywhere—definitely the preferred method if your coil of pipe is long.
You can do this in three stages; it’ll be far less messy if you can do this outside.
The first thing to do is run hot water through the coil; you should ensure that the coil’s end is placed somewhere where the excess water can drain away.
After you have run some hot water through the pipe for a few minutes, you should be able to straighten it out very easily.
Once it’s straightened, you can either hold it there and wait for it to cool or an even more effective method is to then run some cold water through it to help ‘set’ it and hold the shape in place.
2. Submersion
While using the same fundamental as running hot water through the pipe, this is a more convenient ‘hands off’ method.
All you need to do is run some hot water in your kitchen sink and place in the pex pipe coil.
Leave it to soak for about an hour (or more if the water’s still hot); this will soften the material and make it easier to straighten.
Remove the pipe from the water and bend it, so it’s straight.
Then once again, you can simply wait for it to cool.
Alternatively, you can then run cold water through it to help ‘set’ the shape of the pipe.
3. Use Sunlight
Using sunlight to warm the pipe up is a great method as it doesn’t require dealing with water and potentially making a mess in your home.
All you need to do is leave the coil out in the sun for a few hours to warm up and become malleable, then simply straighten it out and bring it inside so it can cool.
However, a word of caution when using this method.
Pex piping manufacturers design this pipe to withstand a few hours of UV light.
But if you leave it outside for too long, those UV rays will actually reduce the lifespan of the pipe.
This is not due to the sunlight itself damaging the pipe but it rather increases the speed at which chlorine will degrade the pipe.
But don’t worry too much; when they say to avoid UV exposure, they are talking about installing it in a place that receives direct sunlight for weeks and months on end – a few hours in the sun won’t make much difference.
Pro tip: You can also wrap the piping in black plastic to help ward off some of the UV rays and also help the pipe to heat up.
Remember, it’s not the UV that’s making it malleable; it’s the heat, so this is an excellent way to increase the efficiency of this method.
4. Unassisted Straightening
Sometimes a little manual coaxing and time can also work well to straighten out pex pipe.
All you need is some kind of method to affix each end of the pipe too.
Something like a vice or some clips can work well here.
All you need to do is affix one end of the pipe to something, manually straighten it out and affix the other side to something.
There should be a good amount of tension between them so it can ‘learn’ to be straight; if it’s too loose, it will just coil back up as soon as you release it.
Leave it in this spot for a few hours, and it should be adequately coaxed into a straight line.
5. Use a Pipe Straightener
Pipe straighteners are small devices that apply counter force to the pipe in the opposite direction to which it’s curling to straighten it out.
It’s a very effective tool that’s strong enough to bend even steel pipe, so it’s more than adequate for pex pipe.
But whether it’s worth purchasing one just for this task ultimately comes down to your budget and how much of the pipe you need to straighten.
If you have a friend or family member who can lend you one for this task, you won’t need to spend any additional money.
6. Purchase Straight Pipes
While certainly more challenging when it comes to shipping and storage, it’s also possible to buy straight pex piping up to 20 feet in length.
They are a little bit more expensive than a coiled pipe, but not by much.
So providing you have enough room to accommodate storing such long pipe sections and it’s within budget for the additional cost, it will save you a lot of time.
The downside may be that you have to find yourself re-bending it anyway if you need a curved section.
7. Pull it through PVC Pipe
In lieu of a legitimate pipe straightener, you can also use a length of PVC pipe that’s large enough in diameter to hold the pex pipe inside.
Simply pull the pex pipe through the PVC pipe to help straighten it.
This essentially holds the pex pipe in a straight position and will help to remove a lot of the coiling.
Repeat this process a few times until it stops yielding any noticeable change; you should find that the piping is much straighter.
8. Heatgun/Hairdryer
While this is a risky method, we will include it anyway, as this might be a good last resort for some.
You can use a heat gun or hairdryer to apply heat to the piping as you straighten it out.
Keep the heat moving rapidly and an excess of heat buildup in a small area could damage the pipe.
Low and slow is the trick here, as too much heat will just cause kinking and compromise the pipe’s lifespan, which may lead to leaks.
9. Use Planks as a Straightening Frame
Almost anything can act as a ‘base’ on which to straighten the pipe, even old planks of wood from your home can work great from this.
It might not be perfectly straight by the end, but often pex pipe is concealed and just needs to be ‘reasonably’ straight.
- Start by getting a plank of adequate length, ideally made from hardwood, so that it won’t bow itself.
- Drill a hole that’s slightly larger than the PEX pipe itself. It must be able to pass through it smoothly.
- Attach the plank to something so it doesn’t move; you can do anything from G-clamping it to the table or tieing it to a tree outside; there must be room on either side of the hole.
- Now we’re going to pass the pipe through the hole several times, which will help to straighten it out.
- Pay attention to the natural direction in which the PEX pipe is curling and lean in the opposite direction to further counteract the bow.
- Repeat this process 2-3 times until it’s as straight as possible. It won’t be completely straight, but it should be far better than before.
10. Use Clamps
Most people with even a mild interest in DIY will have some clamps laying around; we can utilize these to create the desired shape we want from the pipe.
All you need is a large, flat surface to lay your PEX pipe out and clamp it down.
Start by drawing out your desired pipe shape using a pencil; you will use this as your guide. Clamp one end of the PEX pipe down and slowly bend it to the angle you want.
Hold this in place and attach a second clamp to it.
Then repeat this process until you have the entire pipe in your preferred shape.
Leave it like this overnight to help this shape ‘set’.
David Kessler is a CSLB licensed contractor with over 25 years of experience. He is specialized in home building, construction, and electrical works; he also has a keen eye for interior design and, over the years, has collaborated with various architects.
