Water Spike 2

This is a low-tech, low pressure drip-irrigation system consisting of dripping Water Spikes connected by a 1/2" (12.7mm inner diameter) garden hose. The hose is fed by a Bucket, which you can fill with an ordinary watering can. No pumps, no water taps, no electricity required.

Important note: The system would also not work connected to a water tap, since it has way too much pressure.

Alternative

If you change your plants (including their positions) a lot each year and might prefer a system that up-cycles used water bottles instead, check out the first version of the Water Spike (https://www.printables.com/model/1233306) or the Water Injector (https://www.printables.com/model/1233305).

Working Principle

The basic working principle is quite simple: A chain of Water Spikes is connected to a bucket through a hose. You simply fill the bucket, which feeds water to the spikes - thus delivering it slowly to the plants nearby.

[Fotograph here]

The images below show sketches of the basic principle.

So, how many can I connect in a chain?

Some thoughts about that:

Each Water Spike has two water outlet holes with a diameter of 1.4mm each. The bottleneck along the spike-tube-spike connections is the inner diameter of the tube connectors on the spikes, with 10.3mm.

A bit of simple math: This gives the holes a summed up area of about 3.1mm² per spike. The connector has a cross-sectional area of about 83.3mm² - or: about 27 time the area of the water outlets per spike.

In my opinion the problem is a lot more complicated, however. Along the path from the last Water Spike End, to the first Water Spike, the flow rate of the water increases, as implied in the sketch above. (Or rather, it decreases the other way around.) This also increases friction with the inner hose walls and the connections within the chain of the water spikes. Therefore pressure will not be constant along the chain, meaning plants will not get the same amount of water, depending on where they are in the chain…

In short, I'll admit: I don't have enough knowledge of fluid dynamics to give you a proper answer based on physics here.

Personally, I've used a maximum of 11 Water Spikes in one chain and the system seems to work fine. More might work as well, but I wouldn't necessarily recommend it.

The Water Spikes

The spikes come in two forms: The Water Spike and the Water Spike End. The names are self-explanatory: the Water Spike is part of the chain. The Water Spike End ends the chain. The image below shows both in comparison.

The two images below show the two spikes again, but with a cut view on the right side. The water outlet holes are clearly visible in the cut view. Below the outlets, there is a plate, which prevents contact between outlet and the ground to avoid clogging.

Bucket Connector

The bucket should be chosen according to the volume of water needed for your plants. A 17mm hole needs to be drilled in the bottom to fit the Bucket Connector.

The Connector is inserted into the bucket from the top. Sealing can be achieved with a TPU seal ring. A silicone or rubber ring could also be used as an alternative. The Connector is then secured by the Nut from the bottom of the bucket. On top of the connector, the Filter is placed, with a layer of gravel above.

The following pictures show the Bucket Connector and Nut, as well as the Filter.

How to print

I pinted the parts with ordinary PLA so far. My recommendations would be:

• Print the Water Spike / Water Spike End with supports only beneath the tube connectors to bridge the small gap to the print bed. If the notches don't come out perfectly it shouldn't be an issue.
• The Bucket Connector should be printed on its side with support underneath.
• The Nut can be printed simply as is, without any support.
• The Filter should be printed on the face with the holes, with supports being used for the outer ring.

Final Thoughts

If you have any improvement suggestions or criticisms, feel free to tell me. I'm thankful for any comments.