Hello,
a few weeks ago I wanted to build a very simple system to water my plants while I'm away. It's very basic but it's a good opportunity to share ideas in this thread. I've let it run for some time before my holidays to have enough time to check it was working well and to spot any leaks.
The main requirements were
- off-grid water supply. (in other words, some sort of bucket). I’m renting the apartment and I wasn’t too enthusiastic about letting homemade pipework under pressure while I’m away
- it shall be very simple and quick to build as I had other stuff to do before leaving
My dad also has two bay trees that would need watering, so for these I used a large 80 liter plastic trash can, a small aquarium pump (Newa MaxiJet MJ750) and a few meters of clear PVC tubing. These pumps can move a fair bit of water at no load, but they have a very small maximum pressure (1.65 meters of water, so around 0.16 bar)
At this pressure, I wasn’t sure the drip emitters that could be found locally would work, and there was not much time left for testing with other emitters (and I wasn’t sure they would be delivered in time before I left) so I thought the small diameter tubing itself would regulate the flow, so I left the end of the lines open.
The timer is a simple mains powered digital timer that I bought for around 7 euros, I’m sure there are many local equivalents. I can program 20 events, each with {day, start time, stop time}, and “day” can be any single day, or each day, or M W F, or T T S, or MTWTF, or SS
https://images-na.ssl-images-amazon.com/images/I/81A4HYyybjL._SY355_.jpgIt’s quite capable for the price, saves the hassle of DIYing one as Ogden said. Only downside is, its resolution is 1 minute, so one can’t water the plant for say 30s, could be an issue for very small pots if the pump is too strong.
That worked well, so while I was at it I built a second one for a window box in my own place. The pots stay outside and I didn’t want to drill holes through 25cm of hard concrete so I smuggled the pipe inside a vent hole at the top of the window. This is higher than 1.65m so I had to use another pump (a Laing DDC-1T that I already had laying around) which has a greater max pressure (around 3mH2O, if I remember correctly). The downside of this pump is that it can’t be used underwater, so the reservoir can’t be a simple bucket, it has to have an outlet fitting. I used a jerrican from Pressol, model number 21167, that I already had. Also it runs on 12V so I had to use a dedicated PSU. All in all this second system is less pretty than the 1st one, but works just as well.
I even built a 3rd one for 2 more small pots, I’ll spare you the details, it’s just like the 1st one (same pump, same timer, only a smaller bucket). On this last one, the two pots are inside a plastic tray which sits on top of the bucket, and has a hole drilled at the bottom, so any excess water falls back into the bucket. There is a crude filter below the hole (one half of a stainless mesh tea infuser) which will hopefully prevent the pump from clogging with too much dirt.
You may see these 3 in action here (1min, no sound) :
Obviously these were built quickly, and have some drawbacks:
-flow is heavily influenced by tubing length and height. Pressurized systems with drip emitters are way better in that regard (particularly with pressure compensated drippers)
-it doesn’t scale up well, as you need one pump and one timer for each plant (or group of plant that need the same amount of water). A more complex system with a microcontroller, a single pump and several solenoid valves would be better. I’ll may give it a try in the future...)
Two interesting links I found:
https://aces.nmsu.edu/pubs/research/agmech_eng/RR773.pdfhttps://medium.com/@ezheidtmann/low-pressure-drip-irrigation-a-homemade-investigation-364285428417Thank you all, they are some interesting ideas in this thread