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Self Watering Garden - Using recycled water from an air conditioner

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Did you ever notice that your central air conditioner has a hose that connects to the drain? I never really thought about it until one night I almost tripped because ours went across the basement floor. I cut the hose and placed a trash can there to collect the water... I figured that I would just dump it each day.

I was surprised the next day to find that it had filled the trash can and made a fair sized puddle on the floor, and quite a mess with a stack of papers that was sitting there. After some rough calculations I discovered that about 350 gallons (1300 liters) was being wasted annually. (And that was a conservative estimate!)

I decided to install a pump and use this water for my small garden which was right outside the basement door. All I needed was to figure out how to spread the water evenly for the plants.

We have used this system for several years now... as soon as we move into our new home we will install the updated version described here.
 
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Step 1: The Original Design

I actually built this unit in April of 2000, so I have been enjoying fresh vegetables every year for quite awhile now. As well as the original design worked there were a couple of drawbacks to presenting it here as an instructable.

The cross pieces on the original unit were made from a 4-way Tee section that I had modified on my lathe. Since not everyone has access to a lathe to machine the parts, and because I am getting a new house and will rebuild the system anyway, a new way of doing this was devised.

Another change that was made was the area where the water left the house and went to the A-Frame... I had used flexible tubing but after a few years it became brittle in the sunlight. I switched to ridged PVC, but this made the unit difficult to move around. Both of those problems were solved with the new design.
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DanTDM5 months ago

Cool. Use grey water too

mcounter1 year ago
I like your idea of recycling your air-conditioning water for watering your garden. Recycling water in your grow room is a viable option for hydroponic growing. I have found here some simple procedures of recycling water with your existing hydroponic systems in your garden.
tinker2342 years ago
could i add a cheap water filter for the plants
askjerry (author)  tinker2342 years ago
Possibly, just remember that this water is not under pressure as your indoor plumbing would be.
thanks
icarson3 years ago
Using weeper hoses you would lose less water to evaporation as well as getting rid of the frame above the garden. The weeping hose cost far less than the pvc piping.

I use the pump to get it into the rain barrels and then have the weeping hose attached to the rain barrels and let it out as needed.


askjerry (author)  icarson3 years ago
Possibly, but there is also the potential for them to get clogged. This water has no chlorine in it to kill off algae and such... so it could grow in/on the hose and clog it up. The system I built has tiny (1/16 inch) holes on the bottom and larger (3/8) holes on the top so I can poke them with a cleaning tool if needed.

Evaporation never seemed to be a real problem... the ground was almost always wet or moist and since I mixed in a fair amount of gypsum and sand with the soil... it gets wet pretty deeply too.

But your method could be a viable alternative... let me know how it works out for you.

Jerry
The weeping hose is buried 8' down and surrounded by gravel, so no light and algea growth. feeds the water right to the roots. Has worked great for 4 years, knock on wood, spring is finally here, and don't want to jinx it.

magickaldan4 years ago
This is fine for non-edible plants only if  you plan on eating the plant Don't try this!  You can get all kinds of nasty diseases Your AC sucks in all kinds of dust and bacteria such as the flu virus and one of the biggest ones is Legionnaires' disease.
you're spot on, but your reasoning is bad. the reason to not use this system for edible plants is because some AC units have heavy metals (including lead) that can leach into the HVAC water. You won't catch the flu virus or Legionnaire's from plants, only from inhaling colonized droplets.
askjerry (author)  blucolt3 years ago
In this case, the water is running down to the ground through the strings at the bottom of the watering holes. The plants then absorb the water from the ground.

Some water will of course splash on the tomatoes... but they are washed thoroughly prior to consumption.
phillipt3 years ago
I don't have much experience gardening, but my wife and I are starting a "container" garden on our balcony. Our HVAC is installed such that the rear of its closet is to the outside of the condo and on the balcony -- that is, the condensate outlet is already outside and we can very easily implement this system.

What about over-watering? or under-watering? If by chance we under-watered, we could always supplement it the good ol' fashion way.

Could over-watering be a concern?
askjerry (author)  phillipt3 years ago
I doubt that over watering will be an issue unless you live in an area of very high humidity where the garden can't evaporate properly. If that happens, just install a diverter valve to dump the excess away from the plants.

As far as under watering... I had to water the plants sometimes... but not nearly as much as before the system was implemented.
Thanks for the tip and quick response.
dripwater3 years ago
Check out http://www.airigator.com for a complete A/C condensate irrigation system and additional answers to yoour questions
CyborgGold3 years ago
Great Idea! If you want it to be a bit more visually pleasing, you could look up an instructable on how to make PVC tubing look like Bamboo! (It looks amazing)
askjerry (author)  CyborgGold3 years ago
Great idea... I found it... http://www.instructables.com/id/Faux-Bamboo/ Thanks for the tip! Jerry
AmyLuthien4 years ago
Another advantage to using the black hose outside is that algae doesn't build up in it ;)
adam.read5 years ago
Awesome project. We can dump about 120L a day from our dehumidifiers if we leave them on 24x7, and I've been looking for a way to use it. Has anyone thought about mineral leach though? It seems like the condensate should be pretty much distilled water. Should I be adding extra plant-food somewhere in the system?
I'd either use a slow release fertilizer as an amendement when I plant (first choice) or use a liquid fertilizer periodically. Injecting fertilizer into the condensate could result in too concentrated a solution, harming your plants. And most fertilizers aren't meant to be applied continuously. Plus, not all PVC is chemical resistant, which could possibly lead to PVC contamination of the soil (and the food).
askjerry (author)  RoBear6134 years ago
Every year we dig up the bed and remove old roots and so forth. In the spring we generally add some fertilizer and vermiculite to the soil as well as perhaps a bit more soil to replace what was dug out. So it doesn't really seem to be an issue. It's been running for nearly a decade with big crops every year.

Jerry
A good name5 years ago
Bad for your health for PVC's to be near your food.
askjerry (author)  A good name5 years ago
Here in the USA we have PVC plumbing in most houses already... this is for our drinking supply. The water sit in the plumbing for hours and/or days before we turn the faucet. The water from the AC unit and goes into the system briefly... 10 to 30 seconds, then to the ground, the plants absorb from there. I think the water that flows through the house plumbing contains metals as well as clorine, flouride, and other materials would likely be worse for you than the condensation water that only briefly passes through 20 feet of PVC for 30 seconds. Additionally, I think the runoff from the roof and through the rains pouts (also PVC) would be much worse... birds leave droppings on the roof... which may contain disease. The water from the AC unit should be better... I would not call it potable water, but for irrigation it should be fine. There are terra cotta flower pots... but I have seen many made from vinyl... which is a form of PVC... vegetable seedling pots are often ABS or vinyl as well. If you are still concerned, the unit could be constructed from copper plumbing parts, or even galvanized steel. I'm not sure chemically... but I think I would prefer the PVC to the galvanized steel... not a chemist... so that could be debated. Jerry
 
No, the bad plastic (bad additives called phthalates and BPA, actually) comes from the #7 plastic.
PVC is fine, unless it is heated to melting point where it gives off fumes.
girardot4 years ago
This looks nice. I have an AC unit that dumps about 4 to 5 gallons of water on a hot day. I was thinking of a way to use that to water my lawn.
cwopdog5 years ago
I like your idea, I have a 4 ton unit here in S. Fl. and it puts out a lot of water. I plan to incorporate your ideas to water plants and I also have a float pump to spray fog misters on the outside of the condenser unit that draws in the cool air. I put an amprobe on one of the 120 volt phases and measured about 13 amps while the comprossor was running. After turning on the misters, I saw the current drop to 10 amps! This lowers the head pressure and allows your compressor to run a bit more efficient. The condensate is ideal as it is essentially distilled and doesn't tend to cause mineral scale to form on the coils. There are many qreat tricks out these to help save money and cut waste, Best of luck to you and your projects!
Excellent idea. Recycle, use PVC,...couldn't get better than that!
dlw5 years ago
That is a great idea! I wonder if you pumped the water into a small tank at the garden and watered via drip irrigation. You would not loose water to evaporation when you spray it and it can help keep your plants dry (can help with fungus growth). Again, really great idea and design!
chuckr44 dlw5 years ago
The drip irrigation hoses I am familiar with require water pressure. They do not work with gravity fed systems. This is basically a gravity fed system assisted by a pump to get the water "upstairs" or over a hump. After the water is over the hump, the water is gravity fed.
askjerry (author) 5 years ago
We did add fertilizer to the soil at the beginning of the growing season... the location was just a hole in the cement at first... we dug it out and put in some good soil. As for the plants and minerals, etc... the tomatoes we got every year were always very good. We don't spray them with pesticides which i think would be far worse than anything from the system. Also... the diseases mentioned like Legionnaire's were caused by water in a cooling tower... this is water outside that is pumped over and over cooling vanes... it usually has high levels of chlorine added to kill the bacteria... in that case it was improperly maintained and allowed the growth of the bacteria... there were other issues with the circulation, etc. Not a factor with this design. The water comes out of the AC and is pumped immediately outside where it drips into the soil and disperses. The plants get the water via the roots which act as a natural filter... since the water contains no chlorine, bromine, etc... the plants are VERY healthy. The plastic owl was stuck there for show... it was given to me by a friend because it looked good. All I can say is that this system was installed around 2001 or so... (if memory serves me...) we have never had any problems with any of the food. If this concerns you... then just use the water to grow flowers... it is still a good way to use the water instead of throwing it away. Dehumidifier... yes... that would work as well... pump it out to the plants! GREEN! Jerry
its a lion5 years ago
We do this. Except instead of going to plants like that, it runs down to a tree with a few flowers planted around it. We have it dripping into a pipe with a hose running underground out to the plants. Seems to work quite well actually. The tree has grown roughly 15 - 20 feet in around 5 years.
Gaglioti5 years ago
Another great idea for me to work on at home. I love this concept and all the other creators that take the time to show us. Thanks!
killbox5 years ago
Sadly out here in the desert, we rarely get more than a cup or two of water from our ac-units. and we are more likely to have (Evaporative coolers aka Swamp-Coolers) anyway.
vger135 years ago
i would be very careful of this water it may be ok for the plants as long as they are not for consumtion.i have been in the hvac and plumbing line for going on 30years,this water is very bad this is where Legionnaires' disease originated. i wouldnt want this water near anything i am even handling
good work... but plants don't love water from air conditioner (like demineralized) they prefer rain ;-)
Demineralized? Last time I checked, your soil supplied the majority of that. I would agree that they prefer the rain, but only over tap water. Plan is good, but what I would do is us the KISS method. We send the hose into our sump pump. Sump pump empties into our rain barrel system, along with the eve trough. Connect a hose to our barrels (about 220 gallons), and use this for all our watering needs.
This is what I was talking about. Rain and tap water have minerals dissolved in them, but the condensate won't. Will constantly putting distilled water on a garden bed wash the minerals out of the soil? Does anyone know how this will affect the plants?
Thats a point that struck me almost right away on this one. While this may eliminate or reduce the need for watering, aircontitioning and dehumidification systems by nature produce distilled water (condensed from the air in the house), normally devoid of minerals and nutrients that plants require for healthy growth. If your plants are outside and in the earth then you have little to worry about, but a little fertilizer wont hurt. If your feeding potted plants then the soil eventually has to be fortified with fertilizers to keep the plants growing healthy. What happens when they dont have the nutrients they need. First they dont grow as tall or have as much foilage if they grow at all. The plant needs foilage, so it diverts its efforts to leaf growth and and less to fruit growth. Slender stalks wont hold those prize winning tomatoes either. To increase yield make sure they get fertilizer. In the garden back home, my dad tills in cow manuer every year, we get plants that stand 4 to 5 ft tall, one year we had so many huge tomatoes we didnt know what to do with em.
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