Drip Irrigation


The final connection.
The final connection.

 

With one final ‘Click!’ the irrigation system for the front garden is complete!

We have a drip irrigation system in place that runs primarily from the two rainwater tanks in the front garden via 19mm black poly pipe. That gives us 1750 litres to play with. They are connected to the tanks at the back of the house too so that, if the front tanks runs dry, we can pump water to them.

There is a secondary connection to the mains water for really dry times but hopefully we don’t need to use it too often.

Because we’re in the Edible Gardens programme and recording our water use, they have supplied 4 flow meters. Two are flashy and electronic and the others are converted mains water meters. The latter are connected to the tanks because, apparently, they’re better with low flow rates.

 

Low pressure mechanicall meter
Low pressure mechanical meter

 

The drip system has been in for over a year, but was never maximised. We had random dirppers everywhere, mostly of the adjustable kind which I discovered don’t provide a constant flow with different pressures.

I replaced all the adjustable drippers with either 2 or 4 litre/hour types. The label on the bags said that they are consistent over a range of pressures.

All in all, I put in 42 X 2 l/h drippers and 21 X 4 l/h drippers. The 4 l/h went to the base of the trees. Additionally, there is a piece of 40mm pipe going down 30 cm that the drippers feed into. That should maximise the amount of water getting to the root zones as well as reduce loss to evaporation.

The 2 l/h drippers are at the base of the smaller plants and bushes. As they’re generally under trees anyway, this will also help the trees out.

So, we have 42 X 2 =84 litres and 21 X 4 = 84 litres (that match wasn’t planned!) totalling 168 litres per hour of watering time. That matched up closely with the amount recorded through the flow meters on the first test. That was 139 litres. The second test was closer and gave 158 litres. I’m expecting some variation because temporary blockages (thanks Mercy!) and possible variations because of tank water pressure.

Last year we had micro-sprinklers for the annuals, but too much water was still being wasted. Now, all the annuals are in wicking beds or aquaponics, so we can target the water more precisely with the drippers, as well as calculate what we’re using far more accurately. The next goal is to use the mains water and meter to work out the optimal flow rate for our system.

 

Drippers deliver their water more efficiently by taking them down into the root zone.
Drippers deliver their water more efficiently by taking them down into the root zone.

 

Advertisements