compost tea from outdoor utility sink worm bins

cathy_centexAugust 13, 2010

I wanted to share my worm composting system with anyone else who might be interested in a simple, inexpensive setup that allows for regular production of compost tea. This system has worked really well for me for 8 years now (in the warmish to blazing hot climate of Central Texas).

Original posts can be found under the gnat topic, but we were getting a little off track, so here it is again.

I use utility sinks set in the shade under the porch eaves. (In my head, they have a nice wooden screen around them, but unfortunately, reality does not yet match the dream. :)) The sinks are free standing laundry sinks, the least expensive I could find at the home improvement center ($14 eight years ago). I put sand on the bottom to create filtration, and homemade hinged screen covers on top to block critter access. 5 gallon buckets go underneath to collect the compost tea. Not gorgeous, but neat and contained, incredibly time efficient, and never a nuisance.

If you think you'd like to give this a try, start with a good foundation--these get really heavy, and once up and running, are nearly impossible to move without breaking them down. I have concrete pavers set in an inch or so of sand. If you live in a climate that has fire ants, you can place each leg of the sink in a dish/can that will allow you to keep a little soapy water in it (in season) to prevent fire ants from moving in. I didn't do this, and have had intermittent trouble with ants, but nothing that has ever shut me down. Just seems like a wise precaution.

The drain hole of the sink is covered with a piece of window screen, with a couple of handfuls of gravel mounded on top of it. Then 3" to 4" of kids' sand box sand is added, and worms and bedding go on top of that.

The sand filter is multi-purpose: it helps hold all the worms and bedding in place, provides stability to moisture levels, serves as a home for beneficial microbes (which devour potential pathogens), and keeps the tea nice and clean so no particles clog fine watering devices. I've heard that swimming pool filter sand can have diatomaceous earth added to it, so I steered away from that. Seems like it might be abrasive to any worms that come into contact with it.

For the bedding, I use shredded hardwood mulch available in bags at the local garden center. Dampened and mixed with compost and worms, it's a cheap and easy way to avoid shredding paper, and makes a beautiful compost. I know a lot of worm resources recommend paper for bedding, but I found it to be messy and time consuming. Just think of mulch as pre-paper; we've just skipped all the chemical processing that goes into turning trees into paper. Not to mention all the chemicals in the my world, paper goes to the recycling center :)

To start, the bedding may be several inches below the top, giving you plenty of room to add scraps and more mulch to cover. I move to a different quadrant of the bin each time I add more kitchen scraps. Two bins work well for my family of 4, and we do quite a lot of cooking. As the bin matures, you can either harvest the compost directly, or step up the amount of water you run though it to prevent it from getting too full.

I haven't been able to figure out how to add pictures to this forum, but I have some of the completed bins I can share if anyone can suggest the best way to go about that. I know we vermi-composters aren't officially a photo forum, but I've seen them in here, so there must be a way. Have to say I'm really pleased to find such an interesting and creative group of folks to toss around ideas with--I've learned a lot poking around, and just spent the last few days trying to read up on all the good passive solar ideas for the greenhouse I've got under construction. You guys rock!

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eaglesgarden(6b - se PA)

Thanks cathy.

Could you go over your temp. extremes, and the measures you take at both ends of the spectrum? (and maybe an approximate number of days at each).

I'm guessing I won't have the issues you have with heat, but my concerns are freezing temps. (But the help with the hotter days certainly won't hurt!)

    Bookmark   August 13, 2010 at 11:55AM
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Sure. Let me begin by saying that my bins are based on some ideas I got reading Anna Edey's book, Solviva. She created an outdoor, above ground bin out of insulated board to accept waste water from her flush toilet, and piped the worm-filtered water to planting beds; she lives on Martha's Vineyard. She took extra measures for the cold, I adapted mine for the heat. If cold is your issue, you might want to take a look at her website: for a photo and some interesting reading. She is a wealth of good ideas.

That said, last winter we had 11F for our low, and the bins made it through very well. Generally, lows are in the 30's, with freezes coming and going for about 4 months. I throw an old polyester king-sized comforter over the top and fold the edges around it like making a bed. On the coldest nights I turn on a string of little white lights under the bins. I have two side-by side, so they offer each other some mass. They are not in a cold-protected spot, but rather in the coldest spot I could find.

Where they endure Texas summers, which can be brutal. A couple of years ago we had over 60 consecutive days of 100°+. They get morning sun, afternoon shade provided by the roof overhang. The sinks are white, and so reflect heat.

I use them year round, and water them more or less as I need them. They just carry on, and make the job fun!

    Bookmark   August 13, 2010 at 1:55PM
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I really like the idea of a tea machine or water harvest method. I set up a RM tote per previous instructions from other thread (screen over drain w/ 2" of sand- worms and bedding) but it weighs a ton when water was added and needs a solid base. I am now looking for a utility sink to move the tote contents into. These sinks are now $34 + tax and this cost will limit how many of these I will have.

    Bookmark   August 14, 2010 at 9:09AM
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How fine would you say the bedding mulch you buy is? All the bagged mulch I am familiar with is rather coarse and chunky and not something I would find useful for bedding. Is there a specific brand you use? Your method sounds very interesting and worth trying.


    Bookmark   August 14, 2010 at 11:44AM
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eaglesgarden(6b - se PA)

Could similar results be obtained by merely placing an existing tub and putting it onto a stand, that allows for a 5 gallon bucket to fit under the bin? (Of course, a hole would have to be drilled - probably in a corner, with a slight tilt of the bin to allow for proper drainage.)

Obviously, this would need to be set up empty.

    Bookmark   August 14, 2010 at 12:41PM
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Hi Larry

the mulch is labeled "Native Texas shredded hardwood mulch", and is locally produced by Austin Wood Recycling. I believe it is mostly ashe juniper that has been run through a chipper/shredder twice to get that consistency. It's ubiquitous here; we can buy it in bulk or bags from local gardening centers. It's soft to the touch, with pieces up to 2" long, but thin and flexible, similar in consistency to some cypress mulches I have seen. Perhaps that's more available in your area?

and hello again, steamyb, you got right on that! Yeah, they are heavy; be good to your back moving it around. Sorry to hear the sinks have gotten pricey. They are pretty sturdy, though, and have held up well for years now. Don't know if you have a Habitat for Humanity Re-Store in your area, but if so, they might be a good resource for a used one. When I was a kid going to the lakes in east Texas, it seems like a lot of gas stations sold worms for fishing bait, and had long, galvanized troughs to raise them in. I would love to get my hands on one of those one day! Or one of those old Coca Cola drink coolers to sell cokes on ice; anything built to last with a drain in it. Guess you could even use an old bathtub if you had a way to get it up high enough and make it look presentable. Just a little harder to build a nice screen with the rounded corners. (I'll bet my aesthetics-conscious husband just felt a ripple in the force and cringed without even knowing why!)

Would love to hear how these work out for both of you.

    Bookmark   August 14, 2010 at 1:21PM
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eaglesgarden, that would probably work fine, as long as you can get sturdy support under it.

    Bookmark   August 14, 2010 at 2:26PM
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Hi there! I am new to this idea, and my step mom has given me some red wigglers to start off with. My family owns a sawmill, and I literally have tons of sawdust in my backyard. This would be perfect for worm bedding, am I correct? Not to mention free from most any sawmill you can find, as long as you haul it and load it.

    Bookmark   July 13, 2011 at 11:21AM
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