Super Simple Pet Waste Vermicomposter

Earlier this week I decided to (finally) put together a little pet waste vermicomposting system – something I’ve been meaning to try out for quite some time now.

In a nutshell, it is basically a bucket (with lid) with holes drilled in the sides, containing worm habitat (with worms of course) + pet waste, which in this case will be cat doo doo. I’d prefer dog poop but don’t happen to have one on hand – and I don’t think I’m quite ready to ask neighbors to donate, since they already must think I’m pretty weird! LOL

The initial “habitat” in this case is shredded drink-tray cardboard and very-well-aged horse manure.

I decided to drill wide-diameter holes (17/64″) for this system so as to make it easier for worms to move in and out, and plant roots to (potentially) invade. I didn’t go too crazy with them, figuring a cluster of them towards the middle-bottom, along with some up near the top (for ventilation) – on all sides – would be more than enough.

***IMPORTANT NOTE***: For this type of (questionable waste material) system, I highly recommend that you DON’T drill holes in the lid or in the bottom. The aim here is not to send streams of feces-enriched liquid into the surrounding environment! We want this to be as controlled as possible. Similarly, please DO use common sense when deciding if a given location is well-suited for this type of bin. It probably SHOULDN’T be located in the side of a hill (where run-off will just end up pouring in) or in areas with high water-tables or, just generally, in close proximity to bodies of water!

While I am at it, I might as well add the caution that pregnant women and children should NEVER handle cat feces – and really, this type of system should probably only be used by those with at least some vermicomposting experience under their belts!

It’s not a bad idea to smooth out your drill holes a bit, so as to hopefully avoid harming any worms.

As touched on earlier, I created the initial habitat zone by simply mixing shredded cardboard with well-aged horse manure. I made sure everything was nice and moist right off the bat since I planned to add the worms on the same day (more on that in a minute).

As shown in the very first image above, I decided to locate this system directly in front of a big comfrey plant (which has been thriving each year due to its close proximity to my backyard composting bins). This is not close to where food crops are being grown (another location consideration), and I like the idea of having the comfrey – a well-known nutrient accumulator – ultimately converting the wastes into useful biomass (another topic I’ll be revisiting in upcoming posts).

I dug a hole that was deep enough for the bucket to be submerged in soil up to where the ventilation holes are located (second image below is misleading – the dirt had not been moved back yet).

Ok – getting back to the worms…
I ended up adding what was likely the equivalent of one of my “Euro-Red Mix” bags – this added even more top notch habitat material to the system.

Next, I added a thin layer of shredded cardboard, then a layer of cat poop (if people are squeamish about gum, I’m certainly NOT going to bother with images here! LOL), with a final layer of the cardboard over top.

Lastly, I simply popped the lid back on.

I just checked on the system again, and it looks as though – while there a no worms up in the poop zone (not surprised) – there is a lot of critter activity in general, and there are plenty of worms in the habitat material directly below. It’s important to mention that it’s been really hot (by our standards) as well – so I wouldn’t be surprised if a lot of worms are hanging out below where it’s likely a lot cooler.

The possibilities for this type of system in general, are really limitless. I’ll be writing about another similar project I’ve started (in the same vein as “Worm Towers“) very soon.
Stay tuned!

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    • Judith
    • May 31, 2013

    I’m confused. You say not to site this system near food crops, and I agree. But comfrey is a food crop in my mind.

    • Bentley
    • May 31, 2013

    Hi Judith,
    If you happen to use comfrey for food then by all means don’t do as I do! I use the leaves (if at all) as a compost additive – that’s it. Where I wouldn’t want to put this bin is near my tomato plants etc. There is SOME potential for raw fecal matter to end up on the leaves/fruit of surrounding plants.
    I’m certainly not worried about wastes converted by worms and then fed on by the comfrey.

    Hope that addresses your confusion!

    • John W
    • May 31, 2013

    I have dog poop…can’t mail it to you, but I might try this out.

  1. Did you include the kitty-litter? I don’t have a cat so don’t know if it decomposes.

    • thuan
    • May 31, 2013

    B, I have been doing this with dog poo for about a year now using a one gallon plastic planter pot with holes drilled in the side. I can only compost about a third of what the dog produces. I collect the poo and let it sit for about a week before adding it to the compost. In the compost is the usual dried leaves, cardboards, newspaper, and some kitchen scraps. I started with a handfull of worms but the worm population has boomed since then! Every 6 months or so, I have to remove the pot and removed some of the castings. The roots from a nearby grapefruit tree invade and curl into a ball at the bottome of the pot. I not too worried about contamination of the poo, since the dog poo was already on the grass and I can’t do anything to clean that up. Once a week when I water the plants, I water directly into the pot The worms do a great job of composting the dog poo. No smell either! I am so tempted to add small amount of things you should not compost like cheese and meat into the plant pot and see what the worms can do!

    • Paul from Winnipeg
    • May 31, 2013

    Will watch with interest Bentley. We have two fuzzy freeloaders as my Wife likes to call them. We use wood pellets as their bum box material. I would think that would all compost just fine, if a bit slowly. It gets quite fluffy when damp. Thoughts?

    • Bentley
    • June 1, 2013

    JOHN – Let me know if you give it a shot!
    BOREAL – Excellent question! I knew someone would ask! lol
    Since I’ve had to revert back to the clay stuff (tried compostable litter, but ended up getting too expensive given how much they seemed to go through) I knew I’d need to either take advantage of my older cat’s (endearing) habit of leaving it on top of the litter (i.e. get it before it gets coated) or try to rinse it off. The stuff we use is unscented, so I don’t think it will be a huge deal if a small amount of it ends up in the bin.
    Keep in mind, this project is more for testing than it is intended as a convenient and effective way to deal with clay litter cat poop deposits! lol
    THUAN – That’s really interesting! Thanks for sharing. I totally agree re: locating close to a tree (even if a “food” tree) – not likely going to create any hazards there. Glad it has worked out for you! I wonder how much larger the system would need to be in order to handle all your dog waste?
    PAUL – “Fuzzy freeloaders” – love it! haha
    I would think that litter material would be fine in one of these systems, although it would require a much larger container if you were going to try and compost all of it. My guess is that it would be similar to the wood shavings bedding that is often mixed with horse manure (resistant but still offering some habitat value for the worms)

    • John W
    • June 1, 2013

    I am def going to give it a shot. Now I just need to find a bucket. Question…did you bury it just to help keep it cool or did you bury was it your intent to get the nutrients directly to the plant? I would much rather keep it above ground so that I can just dump the finished product into our potholes.

    • Chris
    • June 2, 2013

    One thing which could possibly have an impact on vermicomposting pet waste, is what do you feed your cat (or dog for anyone doing this with dog waste)?

    The reason I ask is I recently (6 weeks or so ago) started my 13 year old cat on a raw food diet, after doing quite a bit of reading on cat nutrition and raw feeding, and among the numerous health benefits that are supposed to come from such a diet over commercial, cooked and highly processed foods, is smaller, dryer, and more biodegradable stools. Which also supposedly have little to no detectable smell, which could make it less unplesant to work with.
    My cat is an indoor/outdoor cat, and as such I never actually see her stools, so I can only go by what I’ve read on that, though I’ve definitely noticed and improvement in her coat and energy.

    Anyway, just thought I’d mention that as something to think about, and I’d definitely recommend at least looking into a raw diet, for the cats (or dogs) health if nothing else. Feel free to email me if you want any more information.

    • John W
    • June 4, 2013

    I started my poo compost pile.
    Its actually going really well. I only feed my dogs dry dog food…and the worms are going crazy over it. I could not find a great bucket so I just used an old car wash pale and drilled some holes in the bottom and side. I don’t have a garden so I am not worried about run off at all. When I go outside to feed my other animals I simply put the hose on mist and douse the bucket with a good bit of water. I am hoping that always being wet will help with over heating. The bucket is in shade, but its getting into the upper 90’s here.
    I looked into the bucket the other night and a large portion of the poo was already broken up and worms were def in it.

    • John W
    • June 4, 2013

    I posted a nice little paragraph on how I started a poop compost pile as well, but it did not post.
    Oh well…
    Anyways…I started mine and it is doing much better than I had expected.

    • Kim from Milwaukee
    • June 5, 2013

    Bentley, you might consider trying another very inexpensive compostable litter…..chick feed starter. I was buying World’s Best Cat Litter at $40/25lb bag, and I read somewhere on the interwebs that it’s exactly the same as the starter which I can get at a farm supply for $15/50lbs!!! And it really works great, composts very nicely, too.

    • Kim from Milwaukee
    • June 5, 2013

    @Paul from Winnepeg…I used to buy the wood pellet litter, it composts beautifully!! Was too expensive for me though, and still smelled a bit as well as sticking to the kitty’s feet when wet. Wasn’t fond of that feature.

    • John W
    • June 5, 2013

    am i the only one who is not seeing all the comments? I get emails saying someone posted on here, but I don’t see any new comments. Even the blog says 13 comments and then when I click on this post only 9 comments are shown.

    • Chris
    • June 6, 2013

    To John W
    Well, assuming you can see the this in your email, I’m seeing all the comments just fine. Including your paragraph about starting your poo compost that you thought didn’t post.
    But one tip, something I always do when posting things anywhere, is select all the text (ctrl A), then copy (ctrl C), so that if something goes wrong in submitting, I can easily just paste it into a new post and I haven’t lost it.

    • John W
    • June 6, 2013

    Thanks Chris. I switched browsers and now I can see all the comments. I just assumed Bentley had erased my post cause I said “poo” instead of “pet waste” and everyone knows how Bentley gets when we use the wrong terms šŸ™‚

    • Paul from Winnipeg
    • June 6, 2013

    @Kim from Milwaukee: Thanks for letting me know that kitty litter will compost. Check mark! I think the price issue may be a local thing; for us here it is the most economical choice. More people burning it so they give us more supply? Canadian Tire and Home Depot are across from each other where we shop and they’re always trying to cut each other on this item. Competition is good. šŸ™‚

    • Bentley
    • June 7, 2013

    Yeah, yeah! I am totally fine with “poo”, Mr. Peanut Gallery!

    As for comments, I have a caching plugin (helps reduce traffic strain on site basically) and it works well – problem is I periodically need to clear the cache etc so that new comments show up.
    So if you add a comment and it doesn’t show up, or you can’t see the comments other people have added (but have come via email) – no worries!

    KIM – very interesting re: the chick starter. Sounds like an interesting business opportunity there (that someone has already taken advantage of). I will have to look into that!

    PAUL – I will have to look for that stuff you are talking about as well!

    • John W
    • June 7, 2013

    I can see them again on Chrome! yay

    • Kim from Milwaukee
    • June 7, 2013

    Bentley, did I read somewhere on your site about chick starter also being a superfood for worms as well?

    • KScott
    • June 8, 2013

    Would the worm castings be appropriate for all use? Just for ornamental plants or for veg/herb garden too? I don’t have access to horse manure…I can use cow manure purchased for garden use; is this addition a “must”? I am anxious to get a few of these going, I must say that I have had some angst over the kitty litter/poop I have entered into the landfills over my cat owning years. The dog is kind enough to poop in the woods…LOL

    • Bentley
    • June 13, 2013

    KIM – I DID try out the chick starter as a food and it seems to offer promise (thanks for the reminder – I can get that at the farm feed shop in town!!), but it IS pretty rich in protein (i.e. nitrogen), so that combined with cat poop would be an ammonia party waiting to happen. Still worth trying though – maybe I could just mix it with lots of bedding.

    KSCOTT – The idea here is not to use the worm castings for anything but rather to put the system in a location where nearby plants can benefit. Horse manure etc is not a must – just a fantastic starter material that makes it really easy to get your worms settled in right away. I would NOT recommend any sort of garden-center bagged manure. These can sometimes contain fairly high salt content etc, and not be worm friendly as a result.

    • Eric
    • June 13, 2013

    Ok, so are you pulling the castings out or is this simply a poo bucket to recycle the waste? I have 2 large labs and they generate some serious poo action. So much so, that we have to pooper scoop at least once a day as to avoid “land mines” as we call them. We have a fairly small yard too. So would this be best near a tree? Would it be best in the shade? I live near Dallas TX and it gets HOT here, ( go figure ) even in the shade I don’t see how the worms can survive in a bucket in that heat. Do you have to open the lid and water it often? Does this ever get full? If so, how do you clean it out, or do you?

    • KScott
    • June 15, 2013

    I get that the nearby plants benefit, but won’t the bin get to an “overflow” point and won’t castings need to be removed? If so, is it safe to use the castings everywhere or just ornamentals? Sorry if my question was not clear.

    • Bentley
    • June 17, 2013

    ERIC | KSCOTT – the idea isn’t really to remove castings (at least not until the bin needs to be cleaned out). As I wrote (in a comment) on my more recent update, the ideal scenario would be to have a series of these bins sitting in close proximity to one another. You start with one of them and when it was completely full you’d move to the next one and so on. By the time you had filled the last one (3 or 4 of them might be an ideal number), the volume of material and moisture content in the first one will have dropped substantially, likely making it much easier to remove the bin and clean it out. Whatever is left in there would likely be totally safe to use anywhere by that point – but spreading it around shrubs and ornamentals might still be the best approach.

    As for really hot locations, such as TX, worms may not be a viable option – even with it buried pretty far into the ground. Simply setting it up without worms should still work fairly well though – you’ll likely end up with a healthy population of black soldier fly larvae anyway – so it will be similar (likely actually faster with the heat and the larvae).

    • John W
    • June 17, 2013

    I live in FL and it has been hitting 90 and feels like its in the 105 degree range. Heat has not been an issue for me. I keep the bucket wetter than I do with my indoor bin, but i figure all the evaporation has kept it safe for the worms. Also it is in some shade during the heat of the day.

    • Tiff from Iowa
    • June 28, 2013

    We recently aquired a pet bunny, and looking up idea’s for hutches on line, saw a picture of a vermipost bin under a rabbit hutch. They called it the perfect system – rabbit droppings feed the worms, worms make compost for the garden that grows the rabbits food. So I’m curious if you or anyone has heard/tried this method? We grow vegetable gardens every summer & I love the idea of putting bunny’s waste to good use. Wouldn’t little balls compost faster than dog or cat? And therefore be garden ready sooner? Or would you still wait until after harvest, to use the vermipost on the garden soil?

    • billye timbes
    • July 21, 2013

    Free! Free! Free! Shred your junk mail—world’s cheapest cat litter!
    I’ve been doing this for several years now and it works very well. I keep a bin of old junk mail & spend some time shredding it every month or so. Also, Old Newspapers.
    There is no litter dust with this method, I have a closed litter pan system which keeps the paper contained pretty well. The used paper breaks down very quickly, I haven’t spent any money on cat litter for years.

    • Jeanette
    • July 21, 2014

    Yay, for Tiff’s question. I am wondering the same thing. Rabbits are herbivores, so their poop shouldn’t be a problem right? I have been adding their poop to the compost pile and now wonder if I can add it to my soon to be built worm bins. I think I can add it just like I would food scraps without concern for any problems, but I am very new to this so appreciate advice. I will be adding the castings to a vegetable garden. Great site, by the way.

    • Martha
    • August 6, 2015

    I live in San Francisco (on the sunny side of town). Would the worms do alright here? I have one Rottweiler/Great Dane and Iā€™d love to be able to put his waste somewhere besides a trash can. One bucket? Two? Iā€™m completely new to all of this, so any help is appreciated!

    • Bentley
    • August 7, 2015

    Tiff/Jeanette – Sorry for the lengthy delay! That is a very well known approach, and as long as you are ok with the rabbits having only a cage bottom as their floor, it should work well. The one important consideration, though, is urine – especially if they tend to pee in the same spot. Salts will build up and more ammonia will be release in that area so you’ll need to periodically dig it out of the worm bed.

    Martha – If I had a rottweiler I’d be thinking more in terms of 2 or 3 full-sized backyard composters with worms. A couple little buckets definitely would not cut it! lol
    Start by adding the waste to the one bin – mixed with cardboard. Make sure to moisten periodically. Once it’s getting on towards full, do the same in the second system. By this point you should be able to stock some composting worms down in the bottom of the first one. Once you have filled the 3rd one, you can probably come back and start adding more to the first – the worms will have an established safe habitat down below so layering the fresh stuff up top won’t be a problem. They will move into bins #2 and 3 on their own.

    • Alice Thacker
    • October 19, 2015

    Hi from London, England! Don’t know if you can help. Most of the ground-based booby traps in my garden are produced by foxes though I do also have a small terrier trying to compete. Foxes are omnivores who eat birds and small mammals, complete with feathers or fur; meat (often decayed meat), fruit, worms, cake, gardening gloves, etc.. Do you have any idea whether such faeces can/should go into your type of
    composter? I imaging coyote poo is fairly similar.

    Thank you!

    • CTwormwoman
    • February 9, 2021

    Back in the early ’90s, the “doggie dooley” system came out. I was one of those who was eager to see such a product. At the time I had five mastiffs which equals a lot of poop.
    It’s a high-end version of your bucket method. Newer revisions have added features including stainless steel components and a step on pedal to open the lid. Basically, you put in the dog poop, add water and then the enzymes aka friendly bacteria. The enzymes were and still are outrageously expensive. I started using rid-ex instead of the brand name enzymes as it is nearly identical but significantly cheaper. It definitely did not work as advertised. Following installation and usage instructions 100%, It didn’t break down even half of the advertised waste. Amazingly, it is still a high selling product. Perhaps for someone with a tiny dog it would work but for someone like myself who still has giant breed dogs, there’s not enough enzymes in the world too consume what they produce.
    Another limiting factor is that I live on the East coast of the United States where we have snow/freezing temperatures from October until May. Right now, there is approximately 26 to 30 in of accumulated snow in my backyard and there is no way on this planet I would attempt to dig the snow off the waist collection system to open up the cover to add the dog waste which would have to be dug out of the snow to be added anyway.
    I see the same problems with the worm system. The worms would replace the enzymes, but there is still weather to be factored in especially in areas with long winters and frequent snow. The bin would have to be very insulated for the worms to manage to survive the winter. Yesterday, the temperature was 11Ā° f and with wind chill, the real feel was -9. I don’t think the worms would be happy for a addition of fresh dog or cat poop. If they were alive at all, they would be in the very bottom all curled up in a ball to maintain heat. Currently, I have two very large dogs and five indoor cats. I use clumping cat litter in the litter boxes. There’s no way to “wash off” the litter. Not to mention, I’m not going to scoop poop and then try to wash the litter off it. I have public water which is not cheap and my sewer bill is directly related to my water usage. So even if I could wash off the litter which I can’t, there would be a water and sewer bill charged related to it. But with clumping litter, washing is not possible. Once it clumps it’s a big hard mass which is the purpose of clumping litter. I wish there were a less costly, more environmentally friendly way of dealing with animal waste especially in cold climates where putting something into the ground is not possible for five or six months at a time. The exception is beneath the cages of meat rabbits. The rabbits are outside year-round,. They have a very warm insulated box to go into as they need in each cage. The heat generated by there never ending poop is enough to keep the snow beneath their cages melted and is also enough heat to keep the worms from freezing. I’m amazed every spring when the ground Just begins to thaw. I dig beneath the rabbit cages and find the most extraordinary pile of black gold with very healthy, very active worms . Working furiously doing what they do best while everything around them is still totally frozen. The key is, the rabbits are always pooping. So there is always warm material being dropped. Unlike collected dog due or washed off cat poop that would be cold, the rabbit poop generates enough heat to keep the worms from freezing and keeps them doing what they do best.

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