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Self-sufficient watering table for outdoor cultivation

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Dear all,


I would like to share with you a pictorial of this ‘self-sufficient’ watering table I recently constructed.






I was looking for a solution to avoid having to continuously water my (mainly) Sarraceniaceae collection and especially during holidays etc. I came up with a design for a setup which collects rainwater in a reservoir and automatically pumps it to the highest watering table above the reservoirs with a solar powered pump in a continuous cycle. This is the original design (sorry, this part is in Dutch):




Because I grow my plants on the balcony (I live in Amsterdam and unfortunately don’t have the luxury of a ‘real’ garden) I first had to find a way to collect the rainwater. Our rain pipe is square and there aren’t any pre-made rain water collectors available for square pipes (only for round pipes). That meant I had to make and weld one myself from zinc metal.




Next I had to make a hole in the side of the rain pipe and slide in the adapter.




To make the cross-over between pipe and adapter inside the pipe as smooth as possible I overlapped the edges with aluminum isolation tape (which is normally used to attach reflective isolation foil behind radiators etc.). Aluminum isolation tape is thin, strong and relatively resistant against corrosion. I also use it to cover the outside of plastic containers when they are in full sun. This reflects the sunlight and keeps the pot and roots cool.

I left the top of the adapter open so in case we get a Dutch ‘flooding’ shower the excess water can find a way out and doesn’t take down the adapter or cause other kind of damage. I made a ‘safety valve’ cover from aluminum which just slides in and isn’t attached permanently. If need be it will just ‘pop’ out so the excess water can escape.




Because the rain pipe is on the shady end of my balcony and the plants are on the sunny (other) side of the balcony I had to put in quite a lot of length of rain pipe (40 mm) to get it all the way to the other side of the balcony (to make the pipes as less visible as possible I hid it behind the plant pots which sit on the outer wall)




I used two reservoirs which contain 2x 150 litres = 300 liters of rainwater. The watering tables themselves contain another 100 liters (= 400 liters in total) and offer a little over 2 square meters of growing space).  I hope 400 liters of water will proof to be enough during longer hot periods without rain, if not I will have to put in another one or two reservoirs. I believe I once read somewhere that one Sarracenia can use up to a liter of water per day on hot days. Any growers who have experience or can confirm this?




I connected both reservoirs with a standard ‘rainwater butt connector’ as low to the ground as possible.




I wanted to filter both the water collected from the roof (it could contain leaves and dirt etc.) and the water which comes back from the watering table above to avoid damage to the solar pump. First I covered the reservoirs with thick polystyrene isolation boards (to reduce evaporation). I then made a square hole to fit in a basket which is normally used for pond plants. I lined this with a filtering cloth used for aquarium pumps. In future I can just take this out, rinse it and put it back. I covered the basket with the cut out lid and made a round hole for the rain pipe.

To catch the water which will be running back from the watering table above I connected an extra pipe to the diagonal rain pipe going down. In this the hose from the watering table above will be inserted. (You may notice I made an mistake here, because the parts were already glued together I couldn’t correct it anymore and had to fit in the additional second (correct) one later on after discovering my error)




On the left I inserted a vertical rain pipe all the way to the bottom into the reservoir which at a later stage will function as a water level indicator. The first water table from Zinc has been placed on top. The size of both tables is 175 x 61 x 20 cm.




To pump up the water I use a solar pump which is normally used for garden fountains (Esotec, Napoli). To prevent damage this pump will automatically shut itself of as soon as the water level is too low. Not all solar pumps have this essential feature. This pump also has enough power to pump up the water to the required height (not all pumps do). I connected a piece of garden hose (13 mm) and placed it in the left reservoir; this to ensure the maximum possible water flow between the reservoirs and to avoid stagnating water. The pump has suction cups to prevent the pump from drifting and to secure it to the bottom.




The other end of the hose is connected to a bronze connector (normally used to connect a garden hose to a watertap)




I then placed the second supporting structure to carry the lowest water table. Behind the doors it’s possible to store, pots, potting medium, plantlabels etc.






These are three close-up pictures of the standard 32mm plumbing connectors I used. These are glued to one end of a standard ‘rainwater butt connector’.








In order to tell how much water the reservoirs contain I made a water level indicator. This is a simple wine cork to which I attached multiple drinking straws (which are very light and strong). On top I glued a colored bead. As soon as the bead is the same height as the top of the pipe I know I need to temporary water my plants until the next rainfall. I will replace the cork every year as I suspect it will eventually become waterlogged






Here you see the solar panel itself. It’s of a decent (not too big) size and can be placed in an angle with a support on the back (inclusive).




A few days after completion the first rain fell (10mm) and I could finally test it. The reservoirs were full to the brim and once the sun came out the pump came into action and filled both water tables quite rapidly. To my opinion it was flowing a bit too fast (600 liters per hour is the maximum capability of this pump) so I had to find a way to reduce the flow. First I shaded just one side of the solar panel. The pump simply wouldn’t work so I had to come up with another way. I then wrapped the solar panel twice in green agricultural sun filtering material. This worked very well and not only is the flow optimal now it also ‘hides’ the solar panel and makes it less visible (you can see the water flowing on the background).




I have been using this system for over a month now and I am quite pleased with it. I can enjoy growing them without having to worry about having to water them on hot days (especially when on holiday). An extra ‘bonus’ is the sound of trickling water which has a bit of ‘Zen’ feeling to it. I haven’t fully used all the new growing space (I haven’t got enough plants yet to fill the space). To reduce evaporation on hot days as much as possible I use the same white polystyrene isolation boards. Over time I’m sure both water tables will be full with plants.




The container with green agricultural sun filtering material on top contains a few Cephalotus plants and one Heliamphora nutans (which all survived the frosts (-5 degrees Celsius) this winter). The plants showed on the picture are still in dormant state. In summer I will post a picture with plants in optimum condition. In the coming months I will keep a close eye on it and see whether the system will continue to work well. I suspect the sun will warm up the zinc metal in full frontal view quite a bit and over time slowly warm up the water. If this is the case I will cover the sides with reflective isolation foil (normally used behind radiators etc.) If there are any other adjustments required I will report it in this forum.


I hope you have enjoyed this pictorial and wishing you happy CP growing this season.





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Quality job, nice work :good2:

I can't see you having many problems with that setup. One comment i would like to make is that i noticed you have siliconed the water butt connector pipe into the bushings. I did this too when connecting four water butts i used to have in the greenhouse, with marine grade silicone. I found out that marine grade silicone doesn't adhere to this waxy type of plastic very well, and i had drips at every connection after a while. A very slow drip and nothing to worry about, but a non watertight seal nonetheless. And my connections were at the back out of sight. I'm just thinking that with your connections being at the front, you may start suffering some drippage from accidentally tapping it with your foot now and again. So you may find you'll want to rotate the two 150 litre butss so your connection is at the back out of the way of accidental knocks.


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Hi Welshy, Thank you. Yes indeed, spot on. This type of waxy plastic simply won't stick to anything (I guess that's why they make the lids of various types of glue packaging's from the same type of plastic). Afterwards I found out the water butt connections on there own are indeed quite sturdy and don't need any extra fortification. I had no other option but to put the connections on the front (where they are indeed prone to damage). Behind the glass wall is my neighbors balcony and I'm sure they wouldn't appreciate a semi circular tube sticking out on their side :ireful1:

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how easy was it to weld zinc with its low boiling point? what filler did you use?

did you also make the reservoirs if so out of what?

A very nice job and you will beneift greatly from it during the summer months

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I think I'd be looking at connecting a smaller pump to the solar panel and removing the shading. The pump will run with lower light levels so being in operation much more often and for longer.


One of these http://www.ebay.co.uk/itm/Solar-Pump-Garden-Pool-Fountain-Pond-Brushless-Submersible-Watering-Panel-/371148927822?pt=LH_DefaultDomain_3&hash=item566a33334e isn't going to break the bank is it.

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  • 2 weeks later...

Hi everyone and thank you for the encouraging words J


  • Hi Mantrid, I did not make the sink water-tables myself so can’t answer your question. The reason for not making them myself is that I don’t have the right tool to bend the metal over such a long length. So I asked a plumber to make them for me. The plastic  reservoir tanks are just mass produced 150 liter water containers available from any an online garden center.
  • Hi Fred, Thanks for the tip. Indeed that’s not very expensive for a water pump. My main aim was to ‘invest’ in a quality pump so I can go on a holiday with the ‘safe’ feeling knowing that if the system fails it can (hopefully) not be blamed on a lesser quality water-pump. Of course you can never be sure and for all we know they all come from the same factory in China J So far it has been working very well with the shading material. It is indeed better to keep the water moving all the time to keep it healthy but when the light levels are low this is usually accompanied by lower outside temperatures which keep the water fresh.


It’s been 3 weeks now and I have to say I am still very happy with it and I haven’t encountered any issues. I recently realized that because the water reservoirs flood over in case of heavy rainfall also the acidic water gets diluted making it less acidic (which my CP’s won’t appreciate). To resolve this I inserted a ‘T’ piece with rubber rings (not glued). When the reservoirs are full enough I simply turn the ‘T’ piece 180 degrees downward and the water won’t fill up the reservoirs. Once the reservoirs are getting emptier I will turn it upward again until the reservoirs are full. On top of this I have also put a big filter bag made of fine mesh filled with peat in one of the water reservoirs to increase the acidity.





Edited by Reinier
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Hi Fred, Thanks for the tip. Indeed that’s not very expensive for a water pump. My main aim was to ‘invest’ in a quality pump so I can go on a holiday with the ‘safe’ feeling knowing that if the system fails it can (hopefully) not be blamed on a lesser quality water-pump. 

 I've been using these 'lesser quality' pumps for over 2 months now without problems. There are three running at present

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  • 6 months later...

Dear All,


I have had the opportunity to test the whole set-up this season and I can come to only one conclusion; it is great! 

Not having to water and let the rain and sun do the work for me is fantastic, I have been away for 3 weeks on holiday and I came back to my plants in perfect health.


One member of this forum asked me whether I investigated whether Zinc isn't harmful to the plants. Because I couldn't find a satisfying answer on the net (any tips on this?) I decided to not take a chance and cover the inside with a non toxic layer of elastic latex (used for roofs mainly). I applied 3 thick layers and in order for the plant pots not to destroy the bottom layer I protected this with rubber doormats which I cut to size.


I also took the opportunity to transform the bottom table into a cold frame by using polycarbonate sheets (used for greenhouses) which I mounted into an aluminium frame. On the inside I applied one layer of polystyrene sheets (4 cm) and in between the pots of the frost sensitive plants I weaved an electric frost protection cable which I turn on manually when frost is expected.

We've endured the first frost at night and it has worked wonderfully well. The cold frame has a lid on top which I can either close fully or leave just open to allow enough fresh air in when it's not freezing.


Unfortunately I don't seem to be able to upload the pictures I took due to maximum amount of pictures reached.


Best to all,



Edited by Reinier
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  • 3 months later...

Very ingenious system that is.  Great work Reinier. 

I always like to be in "construction mode".  Whenever you are finished with your project you can sit back and watch at the great thing that you have build yourself.

I am sure your selfwatering project is one of a kind and will probably inspire some people to work out something similar.  Again great job!

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  • 1 month later...

I just got to see this thread, and it looks very impressive.

I would make one modification - rather than turning down the electrical output by covering the solar panels, I would install a valve on the output of the water pump, and controlling the water flow that way.

It will allow for good electrical usage even on cloudy days, while allowing for easier control over the pumps output.

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