Low Cost Automatic Waterer for Outdoor or Greenhouse

I plan to be away from home for 3-4 weeks, and had bought citrus plants for my lean-to. So I created a very low cost waterer (about £8. including demi-john). It consists of a demi-john part filled with water, inlet and outlet pipes through a non-porous bung. The outlet and inlet are controlled by non-return valves (pet fish anti-syphon valves). As the days temperature increases water is pumped by air expansion from the demi-john towards the plant. As the day cools in the evening water is sucked from a reservoir by the air contracting. I've a number now, with delivery from 50 to 300ml per day.
A nice feature is that on cool days less is pumped and the night gives time for drainage to occur. By altering the volume of air trapped in the demi-john, you alter the volume delivered per day.
I use it indoors and outdoors

I noticed a few postings about absent watering and so for me, this is my solution.

 

Low Cost Automatic Waterer #2

Here's a photo, also in album at higher resolution, of my set up. The reservoir is on the left, a 5l.water bottle calibrated, for my convenience, from the neck down, in litres. The demi-john is in the middle, and the plant on the right.
Demi-john; I tried cork, rubber and silicone, the best is silicone. Drills easily, grips and seals. Rubber too hard needs grease and slips out. Cork too porous unless liberally coated with vaseline and pipe needed epoxy to seal in drilled holes. Metal tube is 4mm. brass, easily bent if heated to dull red in gas flame and quenched in cold water. Matching silicone tubing gives good seal to pipe.
At the ends of the tubing in the demi-john are 2 anti-syphon valves (2£ max. at pet fish store)
At the end of the tubing in the reservoir is an air bubbler(£0.5), acts as filter to prevent grot jamming non-return valves. To the plant I use loose fitting bigger vinyl tubing fixed at the plant end by a scrap piece of the brass tubing.
By the way the diagonal line marked on the demi-john is a vernier level/temperature indicator, so you can see at a glance how much water has been pumped.
This particular set-up gives me 200ml/day with lean-to going from 15deg.C to 35deg.C during the day.

 

Think I may also have a crack at that

 

Well ARMANDII these demi-johns were used to make wine but I don't think the flavour taint lasts for 30 years.

 

Well Shiney, you could do both. Ferment the wine and use the carbon dioxide generated to push water to the plant!!