# DIY Irrigation design: What kind of overlap do I need exactly?



## ovmus (Apr 7, 2021)

Hi all. Sorry for the simple question but thanks in advance for any help. I do appreciate it.

I'm in Bay Area California, 9b. I'm planning on seeding a nearly perfect rectangle measuring 15' x 41' with TTTF in the next week or so. There's no irrigation installed yet so I'm designing from scratch and installing myself. I keep seeing overlap is good, head to head coverage is good but I see diagrams where people have just two sprinklers overlapping certain sections, some have 3 overlaps, some 4 or 5.

How many overlaps is good and how dense do those overlaps need to be?

I have a scale diagram below with 8 imaginary matching rotary heads that I could, for the sake of ease, set to 15' radius. The lightest portions have 2 sprinklers reaching, middle would be 3 sprinklers reaching and darkest would be 4 sprinklers reaching. It seems almost like awkward dimensions to really get prime triangulated sprinklers in there since it's so small.

Is this good enough? If not, what could I do to improve the layout?










Thank you.


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## g-man (Jun 15, 2017)

I dont think this will give you even distribution (every area getting the same rate of water), but it could work. I'm guessing you are going to use Hunter MP2000 at 15ft (If not I recommend you to). Each product has a design guide that tries to show how to do this, but sometimes the layout of the yard makes it hard to find the ideal solution.

In this case, I would move 2 of the 180 to the left or right to get 15ft from the other 180. I would keep everything else right at the same location. This means that some of that 180 will spray outside the 41' (ideally a neighbors yard). Otherwise, keep what you have, but understand that the center will get more water that other areas.


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## ovmus (Apr 7, 2021)

Thank for the thoughts. I was indeed looking at the MP2000 so I'm glad I had the right thought there. Unfortunately the right side of the area is the wood fence (we're packed like sardines here in CA) which I don't want to completely soak and the left side is our little patio/BBQ area so that can't get a ton of water either. It's a tricky area stuck in between everything unfortunately.


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## burntfire (Dec 10, 2020)

@ovmus

Don't judge I did this in paint real quick and is not to scale at all and the overlap is bad... but this is what I would do.



With the geometrical method you intersect at the lines as your horizontal would exceed

I would relocate the horizontal 180s and reduce the 15' throw to around 12' and add full circles at the intersection as well as add vertical 180s on the sides (not shown). You could theoretically move the full circles to the middle of each quadrant and remove the vertical 180s but I would be worried about dryer spots in the corners.


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## bernstem (Jan 16, 2018)

Your initial design is about as good as it is going to get. Adding more heads might get you more even coverage, but with added complexity and cost. g-man's idea will work well if you don't mind irrigating hardscape/house/neighbor/garden or whatever is outside the lawn. Bottom line is that there is no ideal solution for most lawns. Accept the compromises and move on. A bit of overwatering with the original design won't hurt. Watering the garden next to the lawn won't hurt either.


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## ovmus (Apr 7, 2021)

@burntfire Thanks for the input. Unfortunately I already dug out the trenches that match my original design so I'm just gonna go with that for now. It's a small enough area I'm not worried if I have to change it up later. Thanks for your effort.

@bernstem It's such a tight spot I'm not excited about overspray so I'll probably just do my original thought and hope for the best. I may be able to have a couple heads spray farther to help a bit but we'll see. Thanks for your input.


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## San (Jun 21, 2021)

Have you considered just installing 2 programmable sprinklers?

https://irrigreen.com/


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## ovmus (Apr 7, 2021)

@San that looks nice but at $2000 for a 1-head system it's way out of my budget range. Perhaps in the future it's something to look at. Thanks for the info.


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## San (Jun 21, 2021)

I had no clue it was that expensive. That seems rather overpriced to me to be honest.


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## burntfire (Dec 10, 2020)

ovmus said:


> @burntfire Thanks for the input. Unfortunately I already dug out the trenches that match my original design so I'm just gonna go with that for now. It's a small enough area I'm not worried if I have to change it up later. Thanks for your effort.
> 
> @bernstem It's such a tight spot I'm not excited about overspray so I'll probably just do my original thought and hope for the best. I may be able to have a couple heads spray farther to help a bit but we'll see. Thanks for your input.


Ah gotcha then yah the overlap will be fine and you'll get a bitt more water down in some areas.


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