Trenching the irrigation pipe

The Gift of Water



I’m sure it isn’t everybody’s idea of the ultimate Christmas present, but to me it was everything I could ever have wished for. This very special gift was represented by an awkwardly shaped parcel wrapped in pretty paper placed with my gifts under the Christmas tree. I unwrapped it to find a sturdy metal watering can. The parcel was linked to the fact that my husband had also been very busy outdoors as darkness fell on 24 December. All was revealed, when to my joy on Christmas morning, I was taken outside and asked to turn on the brand new brass tap which had appeared overnight, a few short steps from the kitchen door, just along from my huge collection of herbs in terracotta pots.  There was even a new flexible hose with fittings hanging on a support bracket above.  My days of dragging heavy pails from the bore outlet were suddenly over. I had water on hand.


We were living on a 22 acre farm 30kms north of Auckland.  All our energies had gone into getting our glass house tomato business up and running, together with the building of a new home.  However, we had suffered two extremely dry summers in a row and the need to water essential outdoor crops and trees with judicious use of bore and tank water had culminated in our grand watering system. I had diligently played my part in its conception and completion, without realizing I also stood to gain personally.   

We were aware of several changes on the farm following the very dry weather.  The cackling Kookaburras came to visit us two months early and left later.  The brightly coloured chattering Rosellas arrived earlier and there were less burrows and less wild bunnies about.  In January, some of the foliage on our two-year-old Flevo shelterbelts had become decidedly autumnal looking, as the ground dried up and dandelion heads speckled the hard baked front lawn.  The fallen crop of acorns from our row of ninety-year-old oak trees, split open underfoot, like roasted chestnuts.  Our Hibiscus bloomed in March, together with a second flowering of Honeywort and giant Forget-me-nots.  We lost a Peony, the Stephanotis blossomed and a Crepe Myrtle grew stronger and finally bore clusters of raspberry coloured flowers, four years after planting, while the Dogwoods hung on, just.   Our Dachshund, Benjamin, developed swollen lumps on his foot pads and between his toes which were confirmed as imbedded grass seeds as a result of changes to the pasture caused by the altered weather pattern.

As usual our outdoor farm watering system, meant combining real need with what we   could afford – the result another do it yourself project.   After much discussion and draft sketches, a final workable plan was drawn up. We began purchasing rolls of black alkathene pipe in various widths with bags of straight and angle fittings, valve spigots, red flow taps, thread seal tape and glue following in seemingly endless quantities.


We bought a holding tank and started looking for a suitable pump with the right price tag that would be cost effective to run.  Our long search ended when we found an ONGA Australian pump with a capacity of 160 litres a minute at 50 PSI (pressure pounds per square inch).  In reality it was no more than a little household pump capable of pressurizing the water system of a medium sized house, but the key to its success, was not using small diameter pipes.  If we had kept to 20mm pipe we would have needed a more expensive stronger pump with higher pressure.

The other drawback as with most new undertakings on the farm, was time.  With so much on going daily activity, there was no way this project was going to happen at once. The plan was implemented as budget and time allowed and this meant the installation of the watering system was very spasmodic. In fact I remember laying stiffly coiled alkathene pipe combined with the construction of three garden beds, a full eighteen months before the system could actually be used. In conjunction with the preparing the soil, we laid drainage coils and thin water feeder hoses, plus about six sprinkler uprights placed strategically in each 2m x 3m bed.  With the time lapse, when we finally put them to use, fine dust particles filled some of the tiny exit holes, while others had tops missing, knocked off during garden activity. We cleared the holes by blowing very hard into the little uprights and carried out repairs where necessary.


Trenching the alkathene piping at least 500mm underground was almost the easiest part with a plan to follow the Hirepool trencher made shortwork of the digging. An accurate plan was vital, especially with future planting, digging or whatever, having great potential to cause a pipe rupture. The old, check first, dig second rule became our mantra. I was often called upon to help, running out string lines and unrolling seemingly endless metres of 40mm alkathene pipe required to link up irrigation for a further five acres of planting. I quickly discovered that alkathene pipe is unrolled from the inside of the coil, never from the outside - for the uninitiated, impossible tangles are the result.

This covered our grove of fruiting trees - olive, cumquat, greengage, French cider apple, quince, old fashion apple, plum and peach trees, varieties with wonderful names like Early Jewel, Billington- plums; Caville Hiver, Duchesse Anguilleme, Kingstone Black – apples; Matapouri, Nashi – pears.  It was also to provide water for our seven 40m beds of Globe Artichokes, plus the arc of mixed berry plantings, groups and belts of shelter trees, specimen trees and general garden beds.

Eventually the watering system was complete.  The final tally of components was impressive.  We had used 800m of alkathene.  The longest stretch was a 300m length running from the pump to the first off branch. The main lines were 40mm wide with 32mm used for the longer runs and 25mm for the short runs.  The system used 20 brass taps at various key positions around the property (including the one with my name on it).  There were 15 gate valves, which enabled us to be able to finely control the water pressure at that point with a gentle turn to reach the pressure required - a little turn giving around 10 pounds pressure.  Of course, with each additional tap turned on at any one time, the pressure was reduced. 


We used 15mm white PVC pipe for up-stands where taps were required, as it provided rigid support. There were 20 elbows, together with 40 female faucet couplings with an internal threaded end for joining onto pipes with male joints. From the pump itself, two Mac unions depending on a rubber internal sealing ring not glue, made provision for the rest of the system to be sealed off so equipment could be removed by hand if the pump needed to be repaired.  Where glue was required for PVC joints, we used Beta glue as it sets instantly.  20 valve spigots allowed shut off valves to be screwed on to them with each one using a wing back fixing enabling a 90° change of water direction and a fixing for hose taps.  Finally, 20 rolls of thread seal tape were used to seal all threaded joints to ensure we had no leaks.

In the Globe Artichoke beds we used Sumisansui multi 100 trickle watering tape from Japan that permitted even watering at low pressure.  This central flat tape with fine holes equally placed at about 10cm distances on each side, allowed side spray coverage to be adjusted according to pressure and provided more efficient fine directed watering.

The end result, was a system with a pump able to operate either a medium capacity garden sprinkler together with 30 micro-tube trickle lines or two 60m of herbaceous border under soak hose irrigation, plus 12 sq m of other shrub garden with individual micro sprays or two 40m bed of Globe Artichokes.

The set-up made a marked difference to farm efficiency and plant life.  Although we had to make sure the holding tank didn’t run dry, it always seemed like a miracle to me to be just simply able to turn a tap on to have water where I needed it, especially at my kitchen door.