Irrigation - Detailed Planning and Fundamental Issues

After the house construction is completed, we have moved in and summer is just around the corner, we are increasingly focusing on the garden. Since we currently still have a wasteland in front of us, I will plan the irrigation system as soon as possible in order to dig the trenches first.

A few months ago, I thought I was smart and had a well drilled. Unfortunately, I neglected to do further research and was only pleased with the cheap price of the driven well. Now I am slowly starting to suspect that this might not have been so clever.

[*]Apparently, you should not extract more than ~900L/h from a driven well to minimize the risk of clogging. This is already bad news for the number of sprinklers. I should have done better research beforehand…
[*]Yesterday I made a first attempt and connected the suction pump (Grundfos JP5), which the well driller "gave me with it." Using the "bucket method" and the pressure gauge set to 3.5 bar (2.8 bar for Hunter rotators plus 0.7 bar system loss), only a trickle comes out. (Without back pressure, the pump delivers about ~1800L/h for me, with the valve closed there are about 3.9 bar.) The well driller, when addressed, does not understand the problem and says that with 1800L/h I can flood my property in a few hours. Am I misunderstanding the method?
[*]If the situation is really as poor as feared, what would be a possible solution? Get a buffer cistern (1000-2000L), let the suction pump keep it full, and use a submersible pump in the cistern to supply the irrigation system? Any other ideas?

Once these fundamental questions are clarified, I would also like to devote myself to the detailed planning. I have already attached a first version. Our property is relatively extreme at about 15x75m, but so far it does not seem to pose a big problem to me.

You have already done a lot right. Your irrigation planning looks well thought out (over-irrigation, coverage, etc.) Your well builder has no clue. 1800 liters distributed over one circle is not much. With 2 times a week for one hour using rotators, we are talking about 20 liters per m2.

With the bucket method, you have a fundamental error. The quantity is measured without backpressure (so in your case 1800 liters/h). Due to performance losses, it will be somewhat less. With your pressure reducer, you have connected a maximum irrigation circle and tried to install another one behind it.

Now to your actual problem. 1800 liters/h is not much and you will have many circles. With line losses and some safety, you can calculate with max. 1400 l/h. The idea of the buffer cistern is very good. However, you should go a bit bigger. This way, on the days you don’t irrigate or during the day, you can fill the buffer gently for the well. Put an inexpensive tip pump in the cistern. That will give you more throughput.

For example, available in the big store: T.I.P. 30082 deep well pump stainless steel AJ 4 Plus 100/57 AUT with integrated electric pump control, up to 6,000 l/h flow rate

Hi ,

thanks for confirming that I have a misconception. (I just reread how it is described at DVS, I think I misunderstood the topic of "tapping" there)

In my circles I mainly have half and quarter circle 3000 rotators, so 200-420L/h. I had planned the above setup with 6 circles and tried not to strongly exceed ~1000L/h in any of them.

I didn’t find 6 circles too terrible. Is it really that bad? I would have thought that in the early morning hours I can easily irrigate half of the circles and work through them in a 2-day cycle.

Or are there other reasons for fewer and larger circles? What advantage do I have if I then have so much flow with the T.I.P pump that I only have, for example, 3 circles, besides that it’s finished faster and I save some Hunter material?

I’m a bit reluctant to make the entire system (2 pumps, float switch, etc.) too complex. Especially since I now received the all-clear that I can manage 1800L/h (minus loss and clogging buffer).

Your irrigation will run about 30 minutes to 1 hour per zone. Theoretically, it is sufficient to start irrigation after midnight (or later with the 30-minute cycle). Otherwise, the zones can also be split over different days (as you already mentioned). You should not and do not have to irrigate more than 2-3 times per week. 6 zones are not many.

The Tipp pump was only in case you use a cistern as a buffer. Using a cistern as a buffer requires, as you have noticed, increased monitoring effort and monetary investment. Start with your existing pump and the well. If problems arise, you can still replace the pump.

What kind of piping have you planned? PE-HD PN26 DN25? With that, you can theoretically achieve about 3000 l/h at your pressure. If you want to reduce line losses, you could use DN32 piping. Your pump is mainly the limiting factor. Since you designed your zones for about 1000 l/h, that should work.

There are already 275m DN32 PN16 PE pipes ready here

More later when the children are asleep.

To be honest, I find this irrigation plan with circles kind of nonsense. The large square sprinklers from Gardena alone cover the width of your property. I believe with 2 you could cover the entire lawn area and precisely set both the width and the throw distance. You do need a bit of pressure, of course.
It's also a question of what is supposed to grow there? The golf lawn, which is mowed every day, obviously also needs water every day. But it is not desirable – just to say that right away.
A natural meadow can go 2 or 3 days without water and is much easier to maintain. This could be nicely set up in the back area. Trees and bushes, in my experience, do best with a drip hose directly at the trunk. Especially as long as they are still supposed to establish themselves.