I need a smallish perforated pipe to drain a greenhouse bed, oh, mebbe 20' or so. Figuring to use inch and a half PVC, and drill some holes into it. Was wondering about those holes.... Do you suppose a person should make them so that they're only on the upper 50% or 60% of the drainpipe? This would leave an unmarred path for the drained water to travel to another drain. What say ye? Peace, TM
I would leave the bottom 50% with no holes. I would also like to admit that I'm an idiot cause I sold pipe for 10 years and can't remember how the holes were laid out in 4" perforated pipe. I want to say two rows of holes 180 degrees apart. That was for septic though. Water exited the holes, not entered.
Well, without seeing a photo of your setup, it is really hard to say if you do need pipe at all or not? I stopped using pipe in many applications about 20 years ago, as I found that natural/traditional systems in most cases could be made without them. We want to drain places from one point to another...gravel with filter cloth does this much better. Pipe (even perforated) can have water pool under it. If you add sand and gravel around the pipe good, but that is what is doing the real work...not the pipe.
If you actually do have a need, I would use 40 mm pex tubing, and melt or drill the holes 100 mm to 200 mm apart in a "zig-zag" pattern across the top 50% of the pipe...while in place...as it can role. PVC will work too, yet still needs filter cloth sleeve to protect from clogging.