Choose well when installing PVC pipe for your irrigation system. The two main types of pipe are class 200 and schedule 40. The former carries more water for a given pipe diameter, with the annoying trade off that it’s more likely to break. The older the pipe, the more brittle it gets – and the more gunk builds up inside it, making it less efficient at carrying water.
Hello, maintenance! This is a piece broken class 200 PVC. It has thinner walls than its beefier cousin, Schedule 40 PVC. Since the outer diameter is the same, it can carry more water – but the drawback is that it’s more likely to shatter as it becomes more brittle with age. Yes, it’s cheaper than Schedule 40, but this is not a good place to save money: it’s cheaper in the long run to install more robust pipe and avoid possible costly repairs in the future. It should only be used for lateral lines, never for mains that are always pressurized.
This is the standard for mains and laterals: Schedule 40 PVC. Don’t size the stuff below 3/4″ so you can add a head if needed. It’s good for mainlines – constantly under pressure – and laterals – downstream from shutoff valves.
This is a special grade of schedule 40 pipe, intended for potable water, indicated “NSF pw G”. Non-NSF PVC can theoretically leach chemicals into your water, so if you’re ever going to drink water that runs through an irrigation system pipe make sure it’s rated for potable water. (drinking fountain, perhaps?)
The dark gray fitting (“elbows”) are Schedule 80. With thick walls, it’s very tough, but also more expensive than Schedule 40. The most common Schedule 80 use is for threaded pipes (risers) above ground, typically to connect remote control valves to an irrigation system.
There are other options for irrigation line, notably Blu-Lock, with flexible blue pipe held together with fittings that snap together without nasty pipe glue, so it’s very quick to install. The down sides are availability and cost.
These notes are for places where the ground does not freeze. Any type of PVC pipe filled with expanding ice will burst. In cold climates, pipes need to be drained / flushed with air before cold weather sets in. You’ll need to protect any above ground valves, too.