I made an automatic plant watering system using an aquarium pump and electrical timer.
The materials cost me about $60 which I think is a little steep. You could probably do this for about $40 using an air pump instead of a submersible pump, but I had already bought the submersible pump. Here is an instructable about how to do it with an air pump.
Materials List :
- EcoPlus 185 Submersible Pump, 185 GPH ($22)
- Brass Hex Nipple 1/2" M.I.P. x 3/8" M.I.P ($5)
- 1/4" Vinyl Tubing - the standard irrigation kind ($6)
- Quad Adjustable Manifold - Orbit 67005 ($7)
- Thread Seal Tape ($2)
- 7-Day Digital Program Timer - Hydrofarm TM01715D ($19)
- Water Reservoir / Container (free-$10)
I bought the pump, timer, and water container online. The rest of the stuff is from a home improvement store.
I made this because I wanted to put some plants on the top shelf of my kitchen cabinets without having to climb up on a ladder to water them all the time. I also wanted to be able to leave town for a few weeks without worrying about the plants dying. Initially, I was thinking of just using a garden hose timer connected to the plumbing but I asked around and everyone said that this was a terrible idea and that I would end up flooding my kitchen. I decided to set something up with a water reservoir that way if anything went wrong the spillage would be limited by the reservoir capacity.
Step 1: The Water Reservoir
The reservoir should be well sealed to keep the water from evaporating and to keep mosquitoes and other things from getting in there and causing trouble.
I decided to go with a 2 gallon medical sharps container because it has that awesome biohazard graphic that matches my kitchen's zombie/monster theme (the first picture is actually a 1 gallon container not a 2). The sharps container is cool because there is already a hole on the top cover intended for depositing the needles. This is where I run the tubing and water pump power cord. You can also see on the right of the cover there is a red lid attached. Normally this would be used to seal the container when it is full. I popped the lid off, cut a hole under it to use for refilling the reservoir, and then popped it back on. This isn't strictly necessary since I can just pull off the container top to refill it. The bad thing about the sharps container is that it is not meant to be opened and the top has these plastic little locking tabs which I had to cut off to be able to get in and out. Also, the hole in the top is pretty big so I had to wrap some plastic around the tubing to seal it up (see the second picture).
Step 2: Control the Flow
At first I tried to just run a 3/8" vinyl tube from the pump to the plants because the pump comes with a 3/8" outlet adapter (as well as some other sizes). The problem is that this pump outputs 2.6 gallons per minute and most electrical timers are only adjustable in minute increments. In other words, the minimum amount of time for which you can set the timer to turn on the pump is 1 minute, which would pour way too much water, at least for my purposes.
I went to a home improvement store to look for something to adjust the flow and found the Orbit 67005 Quad Adjustable Manifold. It has a knob on the top which lets you regulate the flow rate. It also has 4 outputs so you can water up to 4 separate plants with it (for an extra $5 you can get an 8 output). Since it outputs to standard 1/4" irrigation tubing, you also have a bunch of options in the way of splitters and other types of connectors to help you run the tubing the way you want. The manifold is probably not designed to be used under water but it's been a few months and I haven't had any trouble yet.
To attach the manifold to the pump output I had to use a 1/2" to 3/8" brass hex adapter. I used thread seal tape to make sure the connections were tight. There was very noticeable leaking without it.
After you connect the manifold to the pump you may want to test and make sure that the connection is tight and that you aren't losing pressure to a leak. Put the pump into the reservoir and fill it with just enough water to cover the inlet of the pump. Then remove one (or all) of the little black caps from the manifold outputs and plug the pump in. The only water pouring out should be coming form the uncapped manifold outputs.
Step 3: Run the Tubing and Test the Flow
The ECO-185 pump that I'm using has a lift height of 4 feet. This means that the plant(s) cannot be more than 4 feet above the pump. If you think you will need more than 4 feet of lift you need to get a more powerful pump(e.g. the ECO-264 has a lift height of 6.5 feet).
You're going to want to test that the water can actually make it to your plant, especially if you are near the lift height. If you are watering more than one plant, I would test first with the farthest/highest one so that you don't cut all the tubing only to find that you have to re-position things. Place the reservoir wherever you intend for it to end up, place the pump and attached manifold in the reservoir. Make sure the knob on the manifold is set to greatest flow. Attach the tubing to the manifold and run it to the plants. Fill the reservoir with water and plug in the pump to make sure that the water reaches the plants.
I am just watering one window box so I ran 4 tubes to where the box was going to be and tested the flow. I then drilled 4 evenly spaced holes along the length of the window box to hold the tubing in place.
Step 4: Set Up the Timer And, If Necessary, the Drip Loop
Once you have set up your plant(s) and made sure the pump can reach them you can time how long the pump needs to stay on to adequately water the plants. I used 1 quart mason jars to measure. The time should be in increments of a minute because most electrical timers don't handle seconds. You can use the flow adjuster on the manifold to get it right if you need to.
If your water reservoir is higher than the outlet/timer, set up a drip loop, that is, make sure that the cord drops below the outlet and then comes back up to it so that water can't run down the cord and into the outlet (see second picture).
Set the timer and you are done!
I am watering ivy close to 4 feet above the pump and my timer is set to 2 minutes twice a week. I refill the reservoir using the hose in my sink every 3 weeks. The ivy seems to be happy (see last picture).
P.S. Get a timer with grounded outlets. You are dealing with water here.