High Volume Rain Barrel





Introduction: High Volume Rain Barrel

My wife and I purchased an esthetically pleasing rain barrel for the front yard. After experiencing the benefits there I began looking to build my own system for the backyard for the garden, the landscape, and for play. As I reviewed many online plans and products, I found a number of good ideas. This design I developed differs in that it does not require any drilling/cutting of holes in the barrel for the water flow and the volume of water passed through the system, especially the output, is as high as possible, limited only by the attachment at the end of the hose.

In my case, I knew we wanted a 2 barrel design, the same plan can be followed for a single barrel design. Modifications will be noted throughout the instructable.

Step 1: Out Flow Parts List

Here are the parts that I used and the price. This is for building the piping and valve assemblies to draw water out of the barrel. The parts needed for bringing the water into the barrel are handled separately in step 4. All of the following parts can be purchased at Home Depot.

2 2" DWV MIP Adapter - $0.90 each

2 2" DWV Street Elbow 90 degree Spigot x Hub - $2.01 each

1 2" PVC Pipe (2' section pre-cut) - $2.21

2 2" PVC Tee - $2.49 each

2 2" x 1-1/2" PVC Drain Waste Vent Flush Bushing - $0.86 each

2 1-1/2" x 3/4" PVC Schedule 40 Bushing Spigot x FIPT - $1.27 each

2 3/4" Short Galvanized Nipple - $0.98 each
** I chose not to use this but instead got the PVC schedule 80 (gray) equivalent from my local Ace Hardware for $0.79 to prevent as much metal in the design as possible.

2 3/4" PVC Ball Valve - $2.94 each

2 3/4" MPT x 3/4" MHT adapter - $3.53 each
** While my local Ace Hardware did have this piece in plastic for less, I chose to go with brass here to better withstand contact with the metal threads on my hoses.

1 can of PVC primer and cement - $6.96

For a single barrel design you do not need the Tees or the PVC pipe. You have the option to change the 90 degree Street Elbow with the 45 degree Street Elbow to reduce the bend of an attached hose.

Step 2: Building the Valve Assembly

To build the valve assembly:

1. Screw the 3/4" MPT x MHT (Male Pipe Thread to Male Hose Thread) adapter into one end of the threaded valve.

2. Screw the 3/4" nipple into the other end of the threaded valve. Screw the other end of the nipple into the 3/4" PVC Schedule 40 Bushing Spigot x FIPT (Female Internal Pipe Thread).

3. Insert the assembled parts into the Drain Waste Vent Flush Bushing (2" to 1-1/2" reducer) and then into the 2" Tee.

About sealing the joints:
I found that friction was all that was necessary for the valve assembly. You can also use plumbing tape or PVC cement for the non-threaded joints.

For the single barrel design, you will not use a Tee in the assembly.

I chose to use this design over other designs I found online because of the volume of throughput. Other designs using different spigots or hose bibs would reduce the volume of the water coming out of the barrels as well as the gravity fed pressure. With this design I am able to have 2 hoses connected both receiving almost the full 3/4" diameter of volume through to the hose threads (see the final picture of the volume through the valve assembly). The bottleneck in this system is not the valve or piping, but the 5/8" hose or attachment at the end of the hose.

Also, have younger kids who love to help in the garden, the plastic valve offered the ease of use I wanted for them to be able to fill their watering cans or water guns.

Step 3: Connecting the Valve Assemblies to the Barrels

1. After guaging the positioning of where your barrels will be, determine the spacing between the barrels and specifically between the pipe-threaded bung holes.

2. Cut the 2" PVC pipe (standard hacksaw will do), cutting two small sections for connecting the Tees to the Street Elbows and a larger section for between the two Tees.

3. Insert the pieces between the elbows and tees to make one complete unit.

About sealing the joints:
Using friction or plumbers tape in the joints will allow you to customize the angle of the valve assemblies. If you find that it is leaking, you can cement the joints later. I found this to be beneficial as we could adjust the angle of the spigot assembly to account for filling water cans, water guns, or other items.

4. Remove the two pipe thread bung plugs from the barrels. These are the plugs that do not have the internal threads in the center of the plug.

(I removed the gaskets from the plugs and put them onto the 2" DWV MIP Adapters but this proved unnecessary as the PVC adapters did not screw all the way down into the barrel anyway.)

5. Screw the 2" DWV MIP Adapters into the bung holes of the barrels until tight.

6. Insert the street elbows into the adapters.

With this, the outflow system is complete.

For the single barrel design, insert the vavle assembly into the 60 degree Street Elbow. Insert the elbow into the 2" DWV MIP Adapter.

Step 4: Connecting the Barrels to the Downspout

We had a leftover downspout diverter from the Fiskars Rain Barrel http://www.rain-barrel.com/tuscanyspicegranite.html that we installed at the front door. I used this to supply water to the barrels.

If you choose to use a downspout diverter, there are a number of models available on the internet which connect in different ways. While purchasing one will add approximately $30 to the cost of your project, it will also allow you to use your existing downspout system for handling the rainwater when the barrels are full. See http://www.rain-barrel.com/how_it_works.html for a video explanation of how they work in general.

The most common way for filling the barrels is to cut a hole at the top and install a screen over it to keep out debris and mosquitos. As stated above you must also plan for run-off once the barrel is full. As I already had the spare downspout diverter, it allowed me be create a completely contained system. The only holes drilled into the barrels are a series of 5/32" (smallest drillbit I had with me) holes in the top of the barrels to balance the air pressure in the barrels as they fill and empty.

These are the parts I used for connecting the barrels to the downspout, all from my local Ace Hardware:
1 3/4" MIP to 5/8" barb adapter
4' of 5/8" ID (internal diameter) clear tubing
**This hose fit into the opening of the downspout diverter and also allowed for a larger volume of water to enter the barrels at one time.

1. I used a 3/4" spade bit to drill out the bottom of the one of the internal threaded bung plugs, being careful not to damage the threads.

2. I screwed the bung plug back into the barrel so as to use my homemade wrench to ensure it was tight.

3. I screwed the 3/4" MIP to 5/8" barb adapter into the threads of the bung plug.

4. I attached the tubing to the barb and secured it with a clamp.

5. I followed the instructions with diverter to install it into the downspout and then connected the clear tubing to it.

Step 5: Setting It All Up and Enjoying Free Water

1. Make a level base for the barrels. I used large concrete blocks to raise the barrels off the ground to provide clearance below the spouts for watering cans, hoses, water guns and such. I tilted the blocks slightly to the back to prevent accidental tipping.

2. Position the barrels on the blocks so that they are well supported. I have not found any need to secure them to the back wall of my garage.

Free Water:
With it all in place, I waited for it to rain. A few days later, we received a .21" rainfall. I harvested about 55 gallons from that event. Filling the watering can has never been so fun.




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    62 Discussions

    For a less complicated rain barrel parts group this might work for a lot of folks:-)

    Very nicely done. The barrels, though - where did you get them? Are these specifically made for rain collecting or did you repurpose them from something else?

    1 reply

    You can pick up drums like these from your municipal water authority (often for free) or from just about any power plant (just call them - the worst they'll say is "no", but often they're happy not to pay for disposal). Basically, any of these drums will be safe for use after a few rinses - the chemicals that the drums originally contained have been in use in water treatment for decades.

    Hi, there is some great info here. Thanks already
    I'm about to build my rain barrel system and I'm a bit torn and to which system to go with.
    1. The overflow at the top fills the next barrel (one barrel could be full and the next could only be half full)
    2. They connect at the bottom and all fill evenly at the same time.

    My question is, does one style/system have a benefit over the other?
    Will one system deliver more pressure than the other.
    Thanks in advance

    1 reply

    With the overflow at the top connecting the barrels, you will need valves in the common discharge line (below the barrels) to isolate the full barrels from the barrels being filled - otherwise, the level between the barrels will automatically balance.

    A full barrel will have a higher head pressure (0.43 PSI per foot of "head", or level of the water above the level of the discharge) than a mostly-empty barrel.

    In my system, I have a single fill from the gutters in the lead barrel, a common header connecting the underside of all the barrels, and a valve between each barrel on the common header. I have an extra valve at each end of the common header - one valve is attached to my discharge hose (for using the water). The other valve is in place for draining the tanks as well as to provide future expansion by adding more barrels.

    Very Well done. The step-by-step process was well thought out with excellent instructions. I will be working on a similar project this weekend using this tutorial as a guide.
    Thank you

    If you thredd a steel pipe niple into those bung plugs "caps". The plastic plug breaks out. No drilling is required. = Less chance for blood :)

    I live in Indiana and the problem I had with using a plasic valve is even though I emptied the barrel prior to winter enough water sat in the valve which froze and caused it to crack. I would suggest metal for cold climate valves.

    1 reply

    This is why I have not "cemented" all of the joints together. I trade off the occasional drip for the ability to take the outflow unit off the barrels and take it inside for the winter. That way I could have the high volume throughput of the plastic valve when I needed it and protect the hardware inside when I did not need it.

    Great instructable!! I just ordered a diverter, and I found someone locally selling barrels for $20 each. Looks like I will have a fun little project for next weekend. I originally had a question about how well the barrels would fill due to the input hose being at the bottom, but I then saw it had been answered in another comment.

    Car washes oftten give these barrels away for free. The liquid soap they buy comes in these 55 gallon drums and whats left over in them when u get them can be easily washed out.

    I looked on the internet for local suppliers. I got one from a guy listing them on Craigslist for $25/barrel. Now that this idea is gaining in popularity, I found it harder to find people just giving them away so they don't have to bother with them.

    Just ask the water treatment plant.
    They use them for cleaning chemicals.

    Great instructable!  I called all of our local bottling companies and they ranged in price from $30 each to $10 each.  the $10 was at our Pepsi bottling company.  We were able to fit 9 in our truck.  I think it was a little overkill on my part, but they are useful things to have AND if I don't use them all, I'm sure someone else can use them.

    You are not in a earthquake zone ; So I understand you do not need to secure it . I live in a earthquake prone home; so I think there is a need to secure the rain barrels

    Nicely done. This is what we use in Australia. http://www.gough.com.au/tanks/default.htm typically all new home built here (Queensland) have to have a rain water tank (Barrel) of a minimum size -( from memory I think it is 5000 litres) installed prior to the final building inspection. Not a bad idea for a very limited amount of storage but 3 small suggestions. 1) Pour a concrete slab under the blocks to stop them falling over. 2) use flexible hose instead of rigid plactic pipes between the barrels. If one tilts or falls the flexible hose will not break like a rigid pipe will. 3) Raise the barrels another foot and you will get more water pressure for a slightly longer hose run.

    This was SUCH a great Instructable! I actually became Pro just so I could download the PDF and see all the pictures. THANK YOU for individually labeling and taking pictures of all the PVC parts. While I am quite the handy gal (I work in a theatre scene shop, and know my way around more power tools than the average joe) I was not as familiar with the plumbing. With your clear lists of parts, I was able to find everything I needed at Home Depot with some help from an associate, and make an easy substitution when they didn't have one of the parts I needed. My system is fully built now and tested, I have one or two slow leaks, but I should be able to remedy that with some PVC cement soon. I researched a lot of these rain barrel systems here on Instructables, as well as the internet in general and by far your design was the easiest to follow, assemble, and made the most sense. I will be posting pictures soon!

    2 replies

    Wanted to add the pictures of my finished system! Because I did not have the downspout diverter, I picked up what looked to be a downspout adapter and used that. I also used a barb adapter in the top of my barrel, for overflow, and those were my only changes. Thanks again!

    Garden 2010 047.JPGGarden 2010 036.JPGGarden 2010 037.JPGGarden 2010 038.JPG

    I'm glad you liked the design and that it is working for you. Keep in mind, the volume of water coming into the tanks from the downspout during a heavy rain will be more than can be carried away through your outlet hose. When the barrels are full and it is raining heavily, you may have an overflow situation. Happy watering!