90% of our servicing and repairs involved split, crushed and leaking pipe. It is always the same pipe too. It is the soft black poly pipe known in the industry as LDPE (Low Density Polyethylene). This is the cheap pipe that Bunnings and all the DIY stores will push to sell you. It’s cheap and cheap for a good reason. In short – Its garbage!!

There is a myth that this pipe is far cheaper than the other pipes on the market. This isn’t true. I can buy pvc pipe at the same metre rate as LDPE. I buy crateloads of PVC every dry season. It isn’t uncommon to find several joins in a 2 metre section of LDPE as I’m sure any green thumb would know only too well.

At MB Irrigation, we prefer to use PVC for all underground sprinkler applications. PVC is great because the fittings are cheaper than blue stripe and green stripe and it also comes in 6m lengths and thus stays very straight in the trench. Coiled poly needs to be straightened out and it often has a ‘memory’ where it likes to snake out of the trench if it hasn’t been straightened properly.

There are 4 general plastic pipes available in the irrigation system. These are:

Blue Stripe metric poly:
Standard pressure rating 1250kpa (181psi). This is the king of plastic pipes. It’s durable, very strong and can handle good high pressure. Conforming to strict Australian standards. We use blue strip for mainline applications from the water source to the solenoid valves. It would be a great pipe to use on lateral lines also (sprinkler lines) however the cost of fittings make this uneconomical. This pipe is a metric measurement referring to the outside diameter. Eg 25mm is approx 25mm OD.

Green stripe imperial poly:
Standard pressure rating 800kpa (116psi). Green stripe or ‘rural’ poly pipe was created for the agriculture sector many decades ago. It isn’t to Australian standard yet is a good solid pipe for transfer of water from A to B. Green stripe is a great economical option for farms to move water between dams, tanks, troughs etc. Its cheaper than blue stripe. At MB Irrigation we use green stripe in our above ground garden beds because it won’t split or crack yet can still be punched into for stake sprays etc. This pipe is an imperial measurement and refers to the bore size or internal diameter. Eg 1 inch green stripe has an ID of approx 1 inch

PVC:
Standard pressure rating is 1200kpa (174psi) and 900kpa (130psi). PVC is a great product. It can be used for mainline due to its high pressure rating, and is also the best product for lateral lines (sprinkler lines after the solenoid valve). We use pvc for all underground lateral lines. The great advantage is that the fittings are cheap and about the same price as the barbed LDPE fittings. Fittings can be primed or glued however there is now pushfit instant fittings that we use from time to time which are extremely quick and easy. Measured in metric. The OD always stays the same however the ID changes with pressure rating. The same as blue stripe. 20mm pvc is the equivalent of 25mm LDPE and 1 inch green stripe. This is a good domestic irrigation size

Low Density Poly:
Pressure rating 300kpa (43psi). This product is mass produced purely for the DIY and handyman garden market. It is joined with barbed fittings and clips or hose clamps. It is marketed very well as a cheap and good pipe. There is nothing good about this pipe at all. It splits and cracks all the time and is a menace to the industry. It does have 1 good use however. It is a good product to run above ground for temporary irrigation to help establish spray grass or seeded lawn. Laid on the surface with stake sprays punched in, it is a good option to help bring that grass up to growth. Once the grass is established, grab the sprinklers and keep them but throw the pipe into the nearest skip bin. Our day to day servicing involves repairing this pipe. I cannot stress enough that the customer should NEVER install this pipe. PVC, Green Stripe or Blue Stripe are the answer for underground options. Green stripe for above ground garden beds. Don’t believe the myth that this pipe is cheaper. PVC pipe and fittings are so close to this pipe on price that it becomes a no brainer. The labour content for each job is the same regardless of product used. Why dig all the trenches and do all the hard work, then throw this poor product in. Put the good stuff in and you won’t worry ever again.

MB Irrigation have been installing PVC, Green Stripe and Blue Stripe pipe systems for 12 years and we have never ever seen these pipes split or crack on any of our systems. Don’t get me wrong, a shovel or backhoe will do it but in its natural environment, these products are the best. Low density will randomly split at a time of its choosing, sometimes within a few months of install. LDPE under a rock garden? Our worst nightmare!!

Please help us change the domestic irrigation industry in Darwin. Even if you don’t use MB Irrigation for your install. Please insist on a better pipe whether you are doing it yourself or using a contractor.