If you have ever compared two PVC pipes of the same diameter and noticed one has noticeably thicker walls than the other, you have already spotted the difference between pressure classes. Pressure class (often written as PN, for "pressure nominal") tells you the maximum continuous water pressure a pipe is rated to handle, usually measured in bar.
Why wall thickness changes with class
For a given pipe diameter, a higher pressure class means a thicker wall. That extra material is what lets the pipe safely carry higher pressure without bulging, cracking or failing over time. It also means higher-class pipe costs more and has a slightly smaller internal bore for the same outside diameter, so it is worth matching the class to the job rather than always choosing the strongest (and most expensive) option.
Class 6: light-duty, low-pressure applications
Class 6 fittings are generally used where pressure is low or largely absent, such as gravity-fed rainwater and stormwater drainage. Because the water in these systems is moving by gravity rather than being pumped under pressure, a lighter-walled fitting is perfectly adequate and keeps costs down. Browse our Class 6 rain and stormwater fittings.
Class 9: general-purpose pressure pipe
Class 9 sits in the middle of the range and is a common choice for general household and small commercial water supply lines where moderate, steady pressure is expected. It offers a practical balance between strength and cost for everyday plumbing. See our Class 9 pressure fittings.
Class 16: higher-pressure and mainline work
Class 16 is built for higher-pressure situations -- think mainline water supply, irrigation mainlines feeding multiple zones, or any installation where pressure spikes (such as from pumps or water hammer) are more likely. The thicker wall gives extra margin for safety and longevity. See our Class 16 pressure fittings.
Choosing the right class
As a rule of thumb: check the maximum operating pressure of your system (your pump or municipal supply spec will usually state this), then choose a pipe class rated comfortably above it. If you are unsure, it is always safer to ask -- contact our team or chat to us on WhatsApp with your project details and we will help you pick the right class.