100mm DWV PVC

The main safety concern is regarding the water supply. To avoid contamination of the mains water upstream, in most municipalities, a Dual Check Valve is required at the water connection.

Whenever you’re connecting two threaded fittings, teflon is required. The only exception is whenever either fitting has an O-ring, in this case, do not apply teflon as it may cause the O-ring to not seal correctly. The amount of teflon you apply depends on the application. In any constant pressure applications you look at up to wrapping around the thread up to 20 times, whereas in any non-constant pressure applications, like on irrigation risers, 2 or 3 times around the thread is enough.

There’s no requirement to bury irrigation pipes any depth, but there are a couple of things to consider; Allow enough room to run the pipe under your sprinklers so they sit at the right height & think about going deeper to avoid damage in areas where future digging or planting might happen. 20-30cm is often deep enough.

Pipe sizing is all about reducing friction loss & allowing maximum flow to all points of your garden. There are a number of variables to consider, but in most domestic applications, 19mm Poly Pipe is the common choice. In larger areas, where you may have to run pipe 30-40m to the start of an irrigation zone, or zones with large sprinklers with high flow requirements, you may want to consider upping your pipe size to 25mm of more boost that flow output.

The type of pipe you use depends on the water pressure of the application. For example, in any application under constant mains pressure like before your Irrigation Valves, you’ll need pipe that can cope. This rules out Low Density Poly Pipe & you’ll need to use something like Class 12 PVC or Metric Poly Pipe, these typically have a rating of Class 12, or PN12 which translates to being able to cope with 1200kPa. For irrigation lines after the valves in most domestic applications, Low Density Poly Pipe is ideal. In this situation, the operating pressure is much lower because the water is able to escape out of the operating sprinklers or drip tube & once the valves shut off, there is no static pressure build up.