Improved Improved Continuous Compost Tea Bin

The previous continuous compost tea bin I built worked pretty much as planned. The kitchen scraps I added to it composted down nicely after several weeks and the compost tea that I got from it led to a lush garden.

However, I noted a couple drawbacks to it. First, the 5-gallon buckets I used filled up fast. It's pretty incredible how much compost a small family can generate. Second, the 5-gallon buckets didn't afford much surface area for the water to exit, and with fewer holes, the uppermost bucket that held the compost frequently plugged, even after I added some scrap window screen in between the buckets. Every time it plugged, I had to disassemble the stack, clean it out, and reassemble. Not exactly the minimally maintained setup I was going for.

So, solving two problems at once, I decided bigger does equal better. While I had a stackable drum on hand, I couldn't find a mate, so I bought a couple plastic garbage cans down at the big box store.

Step 1: Drill

I flipped one of the garbage cans over and drilled smallish (1/8-inch, I think) holes until my hand got tired. I probably drilled too many, given how much water it ended up flowing, but if the holes do eventually plug up, I'd like it to keep flowing as long as possible before having to clean it out.

Step 2: Drain

On to the lower bin. Holesaw, bulkhead fitting, boiler drain. I stacked the two garbage bins to get a rough idea of how much distance I had between the floor of the upper and lower bins, then made sure not to drill the hole any higher than that distance.

Step 3: Assemble and Install

Then it's just a matter of fitting the upper bin into the lower bin, stacking the two atop some cinder blocks, and adding compost and water. I'm currently collecting the compost tea with another five-gallon bucket and manually pouring the tea onto my vegetable garden, but the threaded boiler drain will allow me to eventually add a hose.

As mentioned earlier, it flows rather well with the additional holes. With the added space, I estimate it'll take a year or so to fill it. And, theoretically, with what sun that hits it, the black plastic will transfer more heat to the compost, accelerating its decomposition.

Also, because this flows water so well, worms could very well happily live in it. I may get some red wigglers and see how they do.

Step 4: Addendum

I've abandoned this project for a couple of reasons. First, the weight of the compost in the upper can caused the lower can to deform and split toward its bottom.

Second, I've learned much more about effective composting since building this project and no longer see it as desirable to encourage anaerobic environments like this flow-through composter creates. I do still keep my greens and kitchen waste in one of the cans to keep from attracting vermin, but I try to cycle it out as often as possible to add to well-constructed open piles.

If you are still considering building something like this, allow me to suggest using cans made from more rigid material able to withstand the weight of a full load of compost.