Condensation Reclimation Rain Barrel.




Introduction: Condensation Reclimation Rain Barrel.

About: Years ago I ruined a perfectly good home beer brewing hobby by going pro. Being a recovering engineer, I now tinker a lot at home.

Greetings everyone! After a long time lurking, this is my first Instructable, so be nice as I try to figure this out! :)

Okay, the Idea here is that I live in a older house that Was retrofitted to central air conditioning. The air handling unit of that AC was installed in the attic of the house. The condensation drip pan drains from the attic of the house, to the ground where it just.. kinda bleeds out to the ground.

Why not collect that condensation Run off and use it?

Now before any one starts screaming "OMGWTFBBQFREON!".. it doesn't work that way. the freon is on a closed system in the AC, its the stuff that transports hot energy away to make cold stuff... the Water we are collecting here is the condensation form the humidity in the air that is created from that exchange of cold and hot.... It's.. well.. a lot like the sweat on your glass of cold, clear, water as you chill out after a day in the heat, sun and humidity.

During the Dog days of summer, when I've measured it out? that condensation is averaging 25 gallons in a day.

So, yo get down to the nitty gritty of it? this is a basic rain barrel, I'm just harvesting drip water from my AC.

this instructable, as is, only qualifies to houses that have air handling units mounted in upper levels of houses. most newer construction usually has the air handling unit mounted in the lowest level of the house where the condensation runs right into a floor drain. there are float level devices out there that can be used to pump collected condensation water to a desired location. These things are purposely built for commercial ice machines, and add nothing but cost and complexity to this thing we are building.

I built this thing for about $15

The barrel itself came to me free from work. I work for a Microbrewery and the Barrel is what our sanitizing acid comes in. yeah, yeah chill out.. it's food grade. A blend of nitric and phosphoric acid. if you have ever drank a coke or a sprite? You drank this stuff. the MSDS lists it as 1,0,0. Granted, Ive seen the stuff complelty disolve a cadmium socket wrench socket in a week.... but that's besides the point. ;)
in any case, the plastic is food grade and the barrel is complely rinsed out and all is well in the world.

The standing frame is made from five eight foot sticks of outdoor treated 2"x4".  Two sticks are cut in half to make four legs. the rest of the lumber is chopped down to 10 26" sections.

take two legs and frame a 26" stick to the top of the legs. next. measure 13 inches from the base of the feet. Frame in another short stick using the measurement as your base line.
Repeat for the other set of "legs"

use the next four short sticks to lock in the frame. the last two short sticks are laid across the top of the lower frame to provide the support for the barrel.

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: Create and Install the Spigot

So you are collecting all this water... you need a way to get it out of the bucket so you can use it.

The Barrel has two factory ports on the top if it. One has a fine thread, the other a course. in either case. the center of the cap is molded to take a  1/2" pipe fitting. I'll be taking advantage of that. 

parts list is all 1/2" fittings.

1x 1/2" thread to 1/2" butt joint coupler.
1x ball valve.
2x 90 degree elbow fitting.

1x 4' stick 1/2" PVC tubing..
you got some scrap tubing lying around?

under a foot?

you'll be fine

so detail is the threaded coupler into the cap of the barrel. Use a dremel to cut out the pug of the cap. make the cup flush to the Interior diameter of the fitting. Get an O-ring that fits the same diameter of base of the threaded end of the coupler.  Place the O-ring at the inside lip of that hole, then thread in the coupler to the cap.

Now install the caps to the barrel. the cap is threaded, gasketed and water tight when installed properly. There is a special wrench for these caps. but, don't worry about that, you wont be able to use it for the business end cap anyways, a pair of spread out channel locks will work just fine for torquing down the cap, and the coupler.

Install the cap and coupler to the barrel. 

Flip the Barrel upside down and drop into the support frame. Center the tapped hole Between the supports.

Center out the foot brace and use a spade bit to drill out a 15/16" hole.

Peering through that hole, measure out from the flush point of the coupler coming out of the cap to the center of the hole. cut that length from the stock 1/2" PVC tubing.

Cement one end of the first 90 degree fitting to the measured pieces of PVC tubing. the other end goes into the cap coupling with an O-ring.

once that assembly is in place insert the tubing through the hole drilled through the bottom brace to mate to the 90 degree fitting. Measure one inch from the brace and cut off the tubing.
cement the measured piece to the 90 degree, then cement the ball valve to that.

from the remainder of the tubbing, cut out about an inch and a half then loose for that to the remaining 90 degree and the other end of the ball valve

Step 2: The Assembled Unit So Far.

So now we have a 55 gallon plastic drum. the cap has been modified for a spigot and the whole thing turned upside down in frame designed to have its spigot high enough off the ground to accept a watering can,  the spout can be removed and used however we want,
the spigot piping can be disconnected if the barrel needs to replaced, or, for what ever reason.

both caps are threaded. conceivably one could daisy chain a bunch of them together

Step 3: The Device in Place and Installed.

After assembling the device, it is time to install it

The whole thing is positioned as close to the condensation pan drain as possible. In my case. i had to be careful here because all the services for the AC came up and down as a trunk of sorts between the air handler unit in the attic, and the heat exchanger down stairs.

The drain of the condensation pan led outside via a 1/2" PVC pipe ( how convenient!)

A length  of flexible braided 1/2 vinyl tubing was measured to have a inch of tubing in the barrel, and to provide a gentle arc to the drain pipe of the condensation pan.

Once the measurement was taken, the flex tubing was cemented to a 1/2" PVC coupler. Once set and sealed, the coupler is cemented to the drain pipe and the flex is fitted into the Hole on top of the Barrel.

And that should be it, but, we need to take some safety precautions here..

Namely, the barrel needs to be vented to allow air to escape.. that's a simple physics thing right there. Positive air pressure could cause the drain to burp and clog,

But most importantly. the Barrel could over flow. If the level of the water in the barrel covers up the end of the in-feed, it will continue to flow up the drain pipe,and  back up to the condensation pan until THAT over flows, and a full drip pan could cause the coils in the Air handler unit to freeze up.

To avoid all this heart ache.. a few weep holes drilled in the top of the barrel to allow air to escape, and water to over flow before it covers up the water inlet.

Step 4: Let the Water Flow!

As you can see, a small but steady stream of condensation water will flow from the pan and into the bucket. It doesn't look like much, but it can add up to at least 20 gallons a day!

Be the First to Share


    • Trash to Treasure Contest

      Trash to Treasure Contest
    • Wearables Contest

      Wearables Contest
    • Fix It Contest

      Fix It Contest

    14 Discussions


    2 years ago

    Hello - I came across your website tonight because my crawlspace is getting sealed off this week due to a moisture issue and they're laying the vapor barrier down and the whole nine yards. Anyway, I never really noticed all the water that was spilling out onto the ground from my AC condensation until I started monitoring all the moisture in the crawlspace and I wondered if a rain barrel would be the answer to all the condensation water in my yard.

    However, my AC unit is not in my attic -- it's in the backyard and all the duct work is in the crawlspace. My condensation drain line lays on the ground. Here's my question -- if I lengthened the condensation tube and placed it in the top of a rain barrel, would the water drain correctly? It would have to travel upward, instead of spilling on the ground. My concern is that the water won't drain correctly with the drain tube being higher and it might go back under the house and get backed up in the tube.

    I would appreciate any suggestions and comments.


    3 years ago

    I just finished building something similar to harvest A/C condensate to water our garden.

    I had the bright idea to measure how much condensate was flowing from my A/C, and being in the lower Rio Grande Valley of Texas (just 30 miles from South Padre Island), we have plenty of heat and humidity. I'm getting 16-20 gallons of condensate per day... that's enough to provide 3" of water per week to the vegetable garden... and it isn't even summer yet... seems stupid to let it go to waste.

    I used a 32 gallon trash can, drilled a 3/4" hole in the side, about 1" from the bottom, installed a garden hose faucet/spigot. I used 8 cinder blocks (stacked 2 rows high) as a pedestal.

    Then, it occurred to me to see if anyone else had the same idea, and came across your instructable.


    Reply 3 years ago

    I hope you enjoyed it!

    this unit is still in use and doing well.. after all this time, the frame has held up and everything is operating flawlessly with out any maintenance.

    seems you are getting even better and more consistant returns over all. mine is only in use about four months out of the year. but, what its really doing at that point is giving me water during the dry season around these parts


    8 years ago on Introduction

    it'll make things a bit more complex, but have you considered misting water over the condenser? taking water from the inside air, and spraying it over the condenser coil outside should increase the efficiency a bit, and it sounds like you have plenty of humidity to spare.


    Reply 8 years ago on Introduction

    It took me a second but then I think I got it. I'm presuming you are saying to take the reclamation water here and then spraying it at the outside condenser coils to take extra heat away.

    well.. in this operation.. .yer looking at the concept of perpetual motion... while I do have a lot of humidity to spare, there is no way I would produce enough to make the system any more efficient than it already is. we use a lot of condenser units and refrigeration at the brewery and we have installed misters on all the condenser coils we have. When the dog days of summer hit and all the units are being particularly taxed, we crack open a valve and turn the misters on and do exactly what yer saying..
    In this system however, I could never recover condensation water fast enough to the reservoir to make it practical or worth while.. the pump that would be required would consume enough energy to negate any kind of savings in increased efficiency of the unit by misting the condensation coils.

    On a related note.. this is also how window AC units work.. The condensation water from the business end runs to condensation side and gets thrown up by the fan on the coils to increase the efficiency, so, I get what you are getting at.

    Also, little home owners tip.. if your window unit is failing and icing up.. It's usually just dirty, and the condensation water has pooled and is growing algae. when that happens, the condensation water cannot escape, and freezes on the coils.
    take the unit out of the window.. spray the whole thing down with 409 or a proper alcilne coil cleaner, and hose the whole thing down. let it dry out, then reinstall and increase the down angle on the condensation side.

    this is more or less the same reason why in the instrucatable I instruct that the condensation drip tube MUST be installed above the level of the over flow.. other wise the condensation will travel up the drain to the pan, causing the pan to over flow, and ice to form on the heat exchanger side of the unit.

    but.. back to the point.. I think to your post. it takes about three to five days to fill the 55 gallon drum, depending on the weather, you would need a pump to drive the misters. Presumably you could run that pump under solar power, but still. I don't think the system could replenish itself fast enough to make the idea practical.

    Don't think in any way I don't think that is not a GOOD Idea.. I just don't think that it is practical in this application.


    8 years ago on Step 4

    Hey, this is really spectacularly done! I love the nice clean design- this is my favorite rain barrel instructable yet. I live in the high desert but I will use the mounting scaffold to collect rainwater from gutters rather than A/C as it's not humid here in the least. Again- fantastic job and great clear photos!


    Reply 8 years ago on Introduction

    Thank you so much for saying so!
    by all means, please use the design to your own application.
    I Actually dont have any traditional rain Barrels set up at the moment, but I will be putting one up just like this next week or so hooked up to the gutter.

    If anyone takes any thing away from this instructable is the basics of set up of a standard food grade chemical Barrel to rain barrel, I hooked this one up to an AC drip pan, you,or anyone else can hook it up to a gutter, or do it the same way.

    I must add that it has been particularly nasty and humid here in the commonwealth of Virginia. The device has been filling to over flow almost everyday from the wee little drippies from the AC despite pulling the tank down to half full everyday watering the garden.


    8 years ago on Introduction

    THANK YOU. I did a loosely related instructable about harvesting condensate for watering plants and my comments were overflowing with fire and brimstone talk. I'm glad that there's another simple and practical project in this vein.


    Reply 8 years ago on Introduction

    I'm glad to oblige! And don't worry, the ible here is still young so I might get some flames yet!
    I can imagine that the topic of AC's their waste, energy consumption, the potential for harmful bacterial growth, etc might cause some people to become... passionate.
    I certainly wouldn't consider the water to potable for straight consumption, but rather grey water that's fine for watering a garden.
    The device in no way interferes with the operation of the AC itself, and the hotter and nastier it is outside.. the better it works! In fact, in the week it has been installed, it has filled it sel one and a half times!
    Do you have a link to your project so that I may see these commenters concerns?


    8 years ago on Introduction

    Nice spin on the standard rain barrel!!! I wonder if that would qualify as 'Carbon credits' for using the AC? :) Not sure what type of ground you have under the frame, just that if your barrel gets full it's aprox 460lbs pushing down on only 21 square inches of ground. Wouldn't want to see your new project tip over from the legs sinking. Keep up the good work!


    Reply 8 years ago on Introduction

    Thanks for saying so!
    The ground under the Barrel is safe and sound, and I footed the device on top of of top of 1" thick paving bricks. in retrospect, I would've used 6"x12" concrete paver's instead. But rest assured, its not standing on bare ground on its little spindly feet!
    heh! carbon credits.. didn't really think about that during concpet and planning... I just saw a steady stream of water flowing out of drain pan and figured it would better to put some use to it. It gets very hot and humid around here after all. but it doesn't rain nearly enough during the time of year the garden needs it the most. Meanwhile, this thing is steady cranking out water at all times.
    In fact, since instillation two days ago, the device is already a quarter full of water!

    I gotta go into work for a couple ours on my "staycation" tomorrow, so I think while I'm there I'll grab another Acid Barrel to make a standard rain barrel. I gotta fix that gutter down spout anyways after all


    8 years ago on Step 4

    this is a nice instructable. I wouldn't be surprised if it was featured.


    Reply 8 years ago on Step 4

    Thanks! Hopefully after a find and fix all the late night grammar and spelling mistakes!