The days of expensive copper and terracotta pipes are all but behind us – at least they are with modern homes. Almost all modern Australian homes will be fitted with PVC pipes for both water and waste. The good news is, they’re quite simple to replace as all you have to do is cut out and replace the broken section with new components and glue. The real challenge for DIYers is locating the broken section in the first place!
If you’ve found yourself with a water leak or broken pipe, and don’t have the time or resources to locate and fix it, you can obtain a quote from a professional plumber here.
However, if you want to have a go yourself, you’ll find some useful information below.
How to Glue & Join PVC Plastic Pipe
Tip: Make square (flush) cuts for strong joints.
The benefit of cutting your pipes flush with square pipe ends is two fold: firstly, they fit snugly into the fittings which allows plenty of contact area for the solvent cement to work. Secondly, they make a smoother interior surface for better water flow.
A power miter saw and other special tube cutters guarantee square cuts, but you don’t have to buy them. You can do a good job with just a handsaw and an improvised guide. The photo shows an easy-to-use guide that’s made by screwing together scraps of 2×4.
For the best results, use a fine-toothed saw and a blade that’s 3- or 4 inches wide. A hacksaw is a poor choice because the narrow blade tends to wander easily. Special saws for cutting plastic pipe are a worthwhile investment if you plan on doing future plumbing work yourself.
Tip: File off the inner burrs with sandpaper. Left in place, burrs can snag hair and other debris, causing blockages. Simply roll a quarter sheet of 80-grit sandpaper into a tube and flatten it slightly to match the curve of the pipe. Then hold the sandpaper at an angle and sand the inside and outside of the plastic pipe until you create slightly beveled edges.
Mark the pipe and fitting for precise orientation.
By the time you spread the solvent cement on both the pipe and the fitting, and press them together, you’ll only have several seconds to get the alignment right before the pieces are stuck together. That’s why it’s a good idea to make alignment marks beforehand on joints where orientation is critical. Dry-fit the pipe and fitting, using a torpedo level if needed to align the fitting, and make a mark across the fitting and pipe. Use these marks to align the fitting and pipe when you join them with solvent cement.
Tip: Mark the orientation of joints when you dry-fit them. It’s a lot easier than trying to adjust the fit while the cement is hardening.
When applying the cement, you want to ensure you have an even layer over all mating surfaces. Once cement is applied, push and twist for leak-proof joints. Twisting the fitting helps spread the solvent cement evenly to ensure a solid joint.
To keep excess solvent cement from being pushed into water piping, don’t apply too much to the inside of the socket on the fitting. At this point you have to work fast to complete the assembly.
Hold the pipe and fitting together for about 15 seconds until the cement grabs. If you let go immediately, the pipe may push out of the fitting, resulting in a weak joint.
CAUTION! The solvent vapors from the primer and cement can make you dizzy and are dangerous to your health. Make sure you have plenty of ventilation and wear an approved organic vapor respirator when working with primer and solvent cement. Always refer to the instructions on the side of the container before commencing work.
Fix mistakes with a coupling
Mistakes happen, but at least with plastic pipe it’s easy to fix. Simply saw out the affected section, correct the mistake and reassemble the joint with a coupling. In some cases, you can reuse the old section of pipe and fitting. Otherwise, set it aside and cut new parts.
Tip: Buy extra fittings. Having extras on hand will save a trip to the store and often times you can return the extras you don’t use once done.
Allow for shrinkage if you dry-fit the pipes
Most novice pipe fitters find it reassuring to cut and assemble a group of pipes and fittings before gluing them together. It’s okay to do this as long as you’re aware of the pitfalls.
Don’t press the pipe and fitting together too tight. They’ll get stuck and can be difficult to get apart. If a fitting does get stuck, just set a block of wood against the lip and pound the fitting loose with a hammer.
Leaving the fittings loose keeps them from getting stuck, but it creates another problem. You can’t assume that the final assembly will be the same size as the dry-fit parts. When you apply solvent cement to the pipe and fitting and press them together, you’ll lose a little length at each joint. On 1-1/2 in. pipes, this could be as much as 3/8 in. per joint. So keep this in mind if you dry-fit, and allow extra length where fit is crucial.
Use the proper solvent for each type of plastic
There are three common types of plastic plumbing pipe, and each requires a different kind of solvent cement. White or beige pipes (PVC and CPVC) require a primer, while black ABS pipes do not. Always read the label to match the solvent cement to the type of pipe you’re using. Avoid universal solvent cements.
Tip: For a reliable seal, you have to use the solvent that’s formulated for the pipe. All of them contain aggressive solvents and adhesives, so beware of drips and spills.
Use transition couplings to connect different types of pipes
Transition couplings have a flexible rubber sleeve surrounded by a metal sleeve and band clamps. They’re handy for connecting plastic pipe to cast iron, copper or steel – especially if you can’t thread on an adapter!
Each coupling is labeled with all the different types and sizes of pipes it can join. Home centers and hardware stores keep a few varieties on hand. Read the label on the transition coupling to find out which pipe it joins. For less-common connections, contact a local plumbing supplier or ask about ordering a special transition coupling. Rubber couplings without the metal sleeve often aren’t code approved. Ask your local inspector if you’re not sure.
Tip: Slide the pipe ends into the transition fitting, turn the screws clockwise with a nut driver to tighten the bands and seal the joint.
If you would prefer to save yourself the time and stress, you can get a professional plumber to quote here.
Clean Water (Hot & Cold)
This system is designed to be very user-friendly, and because the outside diameter of CPVC tubing is sized the same as copper pipe, the grip-style mechanical fittings can be used on both copper and CPVC. Don’t confuse CPVC with the plastic polybutylene systems that were a problem more than a decade ago. Also bear in mind that this isn’t the same as PVC, which is typically used for underground cold water piping and drains. You can quickly distinguish between the light beige color of CPVC and the bright white of PVC. If you’re not sure, look for the printing on the side of the pipe. CPVC tubing is available at home centers and hardware stores in 1/2-in. and 3/4-in. diameters in 10-ft. lengths.
Are there any drawbacks to CPVC?
You may have heard claims about chemical leaching from CPVC pipes. These claims have been proven false. Studies show that CPVC tubing and fittings are completely safe for home water supplies. In fact, CPVC has been successfully used in homes for more than 35 years. Be aware that many home copper or steel water pipe systems are used as grounding for electrical wiring. CPVC is not a good conductor, so changing to it may change your grounding system. Check with an electrician if you think you’ve broken the continuity of your electrical grounding.
CPVC is not as tough as copper or galvanized steel. Take care not to strike it with a hammer, and be sure to use steel nail plates in wall framing. Because of its flexibility (which can be an asset), you’ll need to support it more often than copper or galvanized steel – we recommend every 32 to 36 in.
CPVC is code compliant almost everywhere. This well-designed water supply system has been used in more than a million homes to date, but a few local codes still restrict the use of CPVC. CPVC is capable of carrying 180-degree water at 100 psi (water in the average home is about 125 degrees at 50 psi).
Contact your local plumbing regulator to see if CPVC is permitted in your area. Note: Never use CPVC for compressed airlines as it may rupture from the pressure.
Tools of the Trade
We recommend buying a special tubing cutter, shown in the picture above. This type of cutter is designed to produce straight, burr-free cuts on CPVC and PVC tubing. You can also cut this pipe with an ordinary fine-tooth saw, but you’ll need to deburr the cut end with a pocketknife, file or sandpaper (see below). This step is absolutely necessary to get a good mechanical or glued connection.
Tip: Cut the CPVC tubing straight and square with the special tool designed for this purpose. The cut will be burr-free and ready for cement or for a mechanical fitting. But for a better fit, chamfer the edge with a pocket-knife. You can also go low-tech and use a fine wood saw in a hand miter box. If you use a saw, remove the burrs from the saw cut.
How to make connections
If you’ve ever done any soldering, you know that you have to get rid of all the water in the adjacent copper pipes and heat the pipe to accept the solder. The special grip-style mechanical fittings shown in the pictures can be used with both CPVC and copper, and will work even if you have some water present in the pipe after you’ve turned off the main and drained the system. These grip-style fittings are much easier to install in situations where pipe condensation would make soldering a real chore.
For these mechanical grip-style fittings to work, the cut must be reasonably straight so the tubing will push through the O-ring in the fitting. The fittings have a one-way gripper ring that grabs the pipe as you push it into the fitting – similar to those Chinese finger puzzles. Once you lubricate the end of the tubing with a drop of dishwashing liquid and push it into the fitting, it won’t come out.
The next step is to tighten the nut (be sure it’s backed off at least one or two turns from tight before you push the tubing into the connector). As you tighten it, the tubing is pushed inside the O-ring. You’ll feel some resistance as you slide the tubing past the gripper ring and then more resistance when the tubing slides into the O-ring. Don’t use a wrench to tighten the nut. Just hand-tighten the nuts on all fittings of this type as a wrench may damage the fitting.
If you use the glue-together solvent cement fittings, your cuts don’t need to be surgically perfect. Just cut the tubing with a tubing cutter or a fine-tooth hacksaw or wood saw, remove the burrs and you’re ready to go. The joint gets most of its strength from the slight taper on the inside of each fitting, so a reasonably straight cut is sufficient for a good fit.
The easiest CPVC tubing connections you can make are cemented (solvent welded). Just like with PVC connections, you want to remove the burrs and lightly chamfer the ends of the tubing. The cement-on tees, elbows and couplings are considerably more affordable and simpler to use than the mechanical fittings, and because of their small size, fit nicely into tight areas.
Some codes require a primer (the purple product shown in the photos). Spread the cement lightly on the inside of the fitting and a bit heavier on the pipe. Go around the tubing several times with the dauber (Photo 6) to work the solvent into the plastic. Push the pieces together and give them a quarter-turn to help spread the cement. Wait at least an hour (longer in unheated areas) before checking for leaks.
Tip: Turn off the water supply, then cut your pipes where you’d like to tie in. For the mechanical fitting shown, we removed 1-1/2 in. of pipe, then had to spread the gap to get the fitting in place. If your situation doesn’t allow this, you can solder a copper tee with a male adapter and run a threaded CPVC female adapter.
Plan for tube movement
CPVC expands and contracts more than copper tubing, especially in the hot water line. A 10-ft piece of tubing can expand in length by as much as 1/2 in. Never butt the tubing against a framing member. Leave a gap, as shown in Photo 8, especially in a long run. Runs longer than 30 ft require a U-shaped detour about 1 ft on a side somewhere in the length to allow for expansion and contraction.
When drilling holes through framing members, you’ll also need to give the piping some space (as seen in Photo 9) to allow the longer horizontal and vertical tubing to move.
Tip: Support your CPVC lines every 32 to 36 in with special CPVC supports. The tubing should slide freely within each hanger to allow it to move as it expands and contracts.