Barrel Basics

Plastic 55-gallon barrel used as a black soldier fly bin

An excellent staple for many home sustainability projects is the simple 55-gallon barrel. Barrels are also available in smaller sizes, but the 55-gallon, being the largest, is the most versatile and the most bang for your buck. IBC totes (usually 275 gallons) and cisterns (can be several thousand gallons) are available in larger sizes, but these usually cost considerably more. The plastic barrels are the best for sustainability projects because metal can leach minerals into water supplies, is subject to rust and corrosion, and by using plastic you are keeping the plastic out of a landfill, where a metal barrel can be easily recycled.

Barrels used in an aquaponics system as a fish tank,
grow beds, and sump tanks

These plastic barrels can be used for many home sustainability projects including rain barrels, aquaponics systems, emergency food storage, manufacturing lye (for homemade soap), manufacturing bio-diesel, raising daphnia and algae (to feed to daphnia), and black soldier fly composting bins. I am even in the process of developing plans to convert a barrel into a wind turbine.
New, these barrels sell for around $175, but they can be found used from home-brew stores, car washes (used to ship soap), bottling companies, as well as Craigslist. Many people (on Craigslist, Farmer's Markets, etc) sell barrels (marketed as rain barrels) fitted with a bulkhead fitting and simple plumbing parts for around $75, but you can easily find raw barrels for $5-$30 on Craigslist and install the plumbing fittings yourself for less than $10 fairly easily. Cheaper barrels on Craigslist are usually not as clean. For example, a barrel may have been used to store used vegetable oil and will have a sticky residue that is difficult to clean out. It is important to ask what was stored in the used barrel, so you can determine if it is too contaminated for your purpose. Also, you will need to decide whether you want open-top barrels (with a removable lid and sealing band), or bung-top. The open top barrels leak when placed on their side or upside down, so they would not be ideal for an aquaponics system (unless you seal them with caulking), but they will be easier to clean out if necessary (for example, if you get algae build up in your rain barrel). Open top barrels are also best for making bio-diesel (ease of stirring), and making lye (ease of adding ash and setting up rock/straw foundation). The bung-top barrels have two holes at the top. One is a buttress thread (not commonly used, the other is a National Pipe Thread (NPT) that is used in PVC pipes. The NPT is a 2" thread that you can easily integrate into piping used in an aquaponics system.
You should also consider the color of the barrel. Plastic barrels come in three colors: black, white, and blue. The black barrels are typically used to ship hazardous chemicals, and the white barrels can attract algae if used for rain barrels because they are slightly transparent. This can be mitigated by painting the barrel. The safest bet is to use the blue barrels.

Uni-Seal used on a black soldier fly bin

When converting a barrel for your desired project, you will need to cut out holes and/or squares and may need to attach pipes through the holes. Squares can be cut easily by drilling holes at the corners of where you want the square with a 2" hole saw and connecting the holes with straight cuts made with a sawzall. This will create nice-looking rounded edges on the cut-out (shown in picture). A hole for a 1" PVC pipe will be drilled with a 1.75" hole saw. To seal the hole the three main methods are: use a barbed fitting (this can be very difficult to get through the hole and may not provide a tight seal), use a bulkhead fitting (pieces inside and outside the barrel thread together with a seal in between, the inner piece can be difficult to place in a barrel with a bung top unless you are cutting out an opening in the barrel), or a Uni-Seal. A Uni-Seal is a compression fitting that goes in the hole and the pipe is slipped through the seal. The Uni-Seal compresses and forms a tight fit without requiring access to the inside of the barrel. A 1" Uni-Seal would be used for a 1.75" hole to allow a 1" pipe to pass through. The picture to the right shows a 2" Uni-Seal on a black soldier fly bin. To slip the pipe through the seal, it is best to file the outside of the pipe that will pass through (so it has a slightly smaller outer diameter) and use a non-toxic pipe grease. Non-toxic is especially important if this is for rain barrels. The dark colored blue barrels usually have a thicker wall, which doesn't allow the Uni-Seal to expand as much, so you may have to use a razor blade to trim the inner portion of the Uni-Seal to allow the pipe to pass through. Just be sure not to trim off too much, so you still have a tight fit. Bulkhead fittings can be found at Lowe's or Home Depot (usually in the electrical section), but Uni-Seals can be harder to track down. So far I have only found them online, see Amazon link below.

With that, you should have a fairly detailed understanding of the type of barrels available and how to select the right barrel for your sustainability project. In future posts I will show more of each type and how I have incorporated their differences into my designs. I hope at this point you're getting excited about becoming self-sufficient and begin looking for a local source for barrels. I'm not sure yet whether I will post next about rain-barrels or black soldier flies. If you have a preference, please vote to the right. Thanks!

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