Without water, growing amazing produce in your backyard is simply not possible. Whether you hand water, rely on rain, use sprinklers or drip line that liquid gold needs to make its way to the roots of your plants or they won’t survive.
Water costs money, and often takes time and effort to apply. Or does it?
Using an Airconditioner to water your plants
If you have an evaporative airconditioner (as in not reverse cycle), a by product of running the cooling system is water, and a fairly significant amount of it. Without any modifications, the water goes straight down the drain, and is good for nothing.
However, with a few quick, cheap and simple modifications you can put that water to very good use in sustaining your plant life.
A good watering system is the foundation of a great garden
How do you collect the water?
The first step to collecting the water from your AC is to find out where it drains from. On most houses, it will come through the eves in a 40mm piece of PVC, and run down the wall and into one of your drains.
Usually an aircon will flush when you turn it off, and at random times during the week. Before you make any modifications, check you have the right pipe!
The easiest way to collect the water is to cut into the PVC pipe coming down the wall, and install a 45 degree elbow (which you can buy from Bunnings for a few dollars). From there, run a new section of pipework down and into a bucket, or watering can, or water tank.
Collecting the water from your AC is a brilliant idea
How much water does it collect?
Every evaporative airconditioner is different, and will produce different amounts of water. Some dump all of their water at scheduled times, and others do it based on salinity levels. Others flush small amounts of water through on a regular basis and do the full flushes much less often.
Each flush on our airconditioner seems to be around 20 – 30 litres of water, and in a week of decent use we can comfortably collect 100 – 150L of water. Of course, this vastly depends on how much you use your airconditioner, and how big and old it is.
We catch several hundred litres a month from our AC to water the garden
How can you apply it to the garden?
If you want to keep it real simple, have the pipework go into a watering can or bucket that you simply empty from time to time onto your garden. Of course, the downside of this is that you can easily forget, and you’ll end up with a pool of water next to your slab, which is less than ideal.
One point to mention is that you should never restrict the water flow from the airconditioner, or you may create further issues. What I mean by this is that even if your bucket, or tank fills up with water, it should freely overflow onto the ground. If you make it so when the bucket fills the water can’t go anywhere, you will end up with water building up inside the pipework back to the airconditioner, which isn’t good.
Our preferred method is to almost completely automate the watering, which we go into below.
What’s your preferred method of watering?
Automating the AC plant watering system
If you can set something up that you rarely, or never have to touch, you have the best of both worlds. We installed a small, upright water tank that holds about 350 litres of water, which the aircon drain runs into the top of. If it fills up completely, the water overflows out the top.
Being able to hold at least a couple of weeks of AC flushes allows us lots of options for using the water. At the bottom of the tank there’s a simple manual ball valve, to keep the water in, or release it.
A ball valve to turn the watering on or off
On the other side of the ball valve is a length of old water hose, that we run to our vegetable and herb garden. This has a number of holes in it (done with a knife, or drill bit), so when you open the ball valve up the water slowly drains out into the garden. The hose at the end is capped off, to ensure the only place water can come out is into the garden.
There are two ways of operating this; we can allow the tank to fill up from time to time and release it when we are out tending to the garden, or we can leave the ball valve open and every time the AC lets water out, it automatically waters the garden. Both work well, and we alternate the systems depending on how warm the weather is, and how much watering we need to do.
Free water from the AC being put to good use on our plants
Is the Airconditioner water safe to use?
The water that comes from your AC is not the same as what you get from your tap. It does not contain the normal chlorine or minerals that you would get from normal water in Australia. That said, its perfectly fine for watering plants with, as long as its not the only water that they receive.
I certainly would not recommend drinking it, as the water has run through the pads in your airconditioner for some time, and likely has pollen, dust, algae and other muck in it.
As long as your garden gets other water its perfectly fine
Doing it on the cheap
One of the reasons this little project is so good is that it doesn’t cost much at all. You might need to buy a couple of PVC elbows and a small length of pipe, but the tank, or bucket, or container can be sourced from off the side of the road, rubbish tips or second hand on Facebook marketplace or Gumtree.
I wouldn’t ever go out and buy a new tank, and spend a significant amount of money on it as the return simply isn’t there.
What’s the point of it?
Save a tiny amount of money
As of right now, we pay $1.827 and $2.434 per kilolitre. Water in Australia is extremely cheap; you are literally paying 18 – 25 cents per 100 litres of water, plus the normal service charges (which you would pay regardless).
Environmental benefits
Reducing consumption, being self sufficient and making good use of the waste you create is a great idea (like worm farming and compost!), so rather than flush a heap of water down the drain you can redirect the AC water to your edible (or even non edible) garden
Much like composting, this reduces our footprint
Make your life easier
Instead of spending 20 minutes hand watering our garden a few times a week, we can leave the ball valve open and know that each time the aircon flushes water our vegetable garden is getting a good drink.
When you have a number of gardens that need hand watering, reducing the time you have to spend outside is a great way. Instead of watering, you can be pruning, cleaning up, planting seeds, squashing caterpillars or picking delicious produce!
There’s more important things to be doing than hand watering!
Watch out for mosquitos
One extra tip that I will make mention of is that mosquitos love any water that isn’t agitated. By this, I mean that if you leave a bucket of water outside you will end up with mosquitos breeding, and that’s not a good thing.
We had this initially, and ended up putting an old sheet over the top of the tank, so they can’t get in to breed.
Collecting water from the roof
There are a lot of people who collect rain water from their homes. This can be used for drinking, or for watering your plants. I have investigated this, but to modify our setup would cost a fair chunk of money and the return just isn’t there.
If we build again, it will be done so we can collect the water more easily!
I looked at collecting rainwater, but its too hard to retrofit without spending substantial money
If you are looking for a cheap, easy and great way to water your plants, consider hooking your AC drain line up to a small tank, and watering your plants!
