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Pet Waste Composting

If you’ve read a fair bit about backyard composting you will likely know by now that one of the cardinal rules is “don’t add pet waste to your compost bin”. This advice certainly has merit, at least as far as a regular compost bin goes (i.e. one you add your kitchen waste to, and eventually empty for the garden). After all, these materials can contain various pathogens, and aren’t exactly all that enjoyable to work with.

I should mention that the term “pet waste” is actually far too broad to be used in this context. There are many different types of pets out there, and a lot of them produce waste materials that make for an excellent addition to your compost piles. Really, any of the herbivorous rodents (is there such a thing as a carnivorous rodent – haha?) – such as rabbits, gerbils, hamsters, guinea pigs – will create some quality compost fodder for you. It will be very easy to work with (not wet and smelly) and there won’t be the same risks involved.

I think the ‘no pet waste’ rule is definitely more applicable to carnivorous (or at least omnivorous) animals. Of course, the two most popular pet poop produces that fall into this category would be cats and dogs. Both of these animals produce wastes that are not only unpleasant to work with in general, but they can also contain nasty microbes as well.

Cat waste in particular warrants extra caution, since it can contain a parasitic protozoan called Toxoplasma gondii. This organism is relatively harmless for many people who become infected, but it can be a serious threat for pregnant woman (it can harm the unborn child) or those with compromised immune systems. Just so you know, most cases of Toxoplasmosis actually result from the consumption of raw meat, NOT from contact with cat feces (see, so there’s no need to get ultra-paranoid about it – unless of course you like your steaks rare!

While I definitely DON’T recommend adding dog and cat waste to your ‘regular’ bins, I do in fact recommend setting up a completely separate system to handle these wastes – after all, why bag it up and send it off to the landfill when you can easily process it yourself and take advantage of the extra source of plant nutrients as well.

A pet waste composter should be set up a good distance away from your other composting systems and vegetable gardens, and as far as possible from the nearest water body (at least a good 100 yards or more). You can start by simply digging a hole in the ground – perhaps 2-3 feet deep and 2 feet across. Once the hole is dug you should add a nice thick layer of shredded cardboard, or some other carbon-rich, absorbent material (coir, shredded paper, aged straw etc) in the bottom. I would also recommend using some sort of enclosure over top. A regular plastic backyard composter will work fine. Aside from leaving you in control of the amount of water added (the last thing you want is to let it get flooded), this will also allow you add a lot more material, and should even help to ward off any curious children/animals.

Now all you have to do is start adding your poop (well, not YOUR poop – although I suppose you could – haha!), along with more bedding material and a sprinkle of water with each deposit. If you leave one of these systems to sit for a couple weeks or so without adding any more fresh waste (you might want to start up a second system), you could also add some composting worms. The worms would help you turn the material into compost much more quickly than would occur by simply letting it sit – but the worms definitely need a buffer zone from the fresh waste materials (hence the suggestion to let the system age for a bit) since it is a little too potent (with ammonia etc) for their tastes.

I wouldn’t personally harvest the compost from these composters – I would more likely try to put them in a strategic location so that surrounding trees/shrubs could take advantage of the rich compost being produced.

[tags]pet waste, dog poop, cat poop, pet waste composting, composting, composter, backyard composting, worm composting, vermicomposting, pathogens, toxoplasmosis, compost bins[/tags]

Written by Compost Guy on May 7th, 2008 with 18 comments.
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Get your own gravatar by visiting Simon
#1. May 8th, 2008, at 2:08 PM.

Although I’ve not started doing this myself yet I have recently taken part in a similar discussion with one extra being add a layer of Bokashi bran every now and then so that the EM’s can get to work on the stuff as well, thereby helping to neutralise the smell as well speeding up the composting process as well.

Well, that’s the theory…

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#2. May 8th, 2008, at 2:12 PM.

That is definitely an interesting idea, Simon!
I’d certainly be interested to find out how well that would work.
It’s days like this I wish I owned a dog.

Get your own gravatar by visiting Anthony
#3. May 8th, 2008, at 3:26 PM.

Thanks, this is good information. I plan on pointing people to this url whenever I get questions about composting pet waste.

And from now on, whenever I think of poop, I’ll think about your site. :)

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#4. May 8th, 2008, at 3:31 PM.

Haha – thanks Anthony…I think!

Get your own gravatar by visiting cultiv8
#5. May 10th, 2008, at 2:12 AM.

What about carnivorous reptiles? Lizards, snakes, etc…

Would their waste make suitable compost? (Many species also produce solid urates.)

Get your own gravatar by visiting Satori
#6. May 18th, 2008, at 4:21 PM.

Although you were just joking when talking about composting “YOUR” poop, it actually is possible.

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#7. May 20th, 2008, at 7:55 PM.

Hi guys – sorry for the delays getting back with my comments!

Cultiv8 – I would imagine that reptile wastes would work well in a composting system, although I wonder if they might be pretty strong (like poultry manure). I’m also not sure if they contain any serious pathogens.
I’d suggest using them in moderation (or in a pet was composter) and mixing with lots of carbon rich materials like staw, shredded cardboard, leaves etc.

Satori – While my comment was indeed somewhat ‘tongue in cheek’, I’m actually very open the concept and hope to one day have my own (vermi)composting toilet.


Get your own gravatar by visiting Peter Ritchie
#8. June 9th, 2008, at 1:20 PM.

I tried one of the commercially available plastic sump affairs to which you add water and a composter liquid. The concept is that it should have stones and drainage around it by way of a pit so that the poo dissolves and drains away. It worked for a bit but blocked up after a relatively short time and is therefore useless. Sounds like you need a lot of space for yours to keep it away from everything, not to mention the smell. I would love to find a solution. Currently I have a bucket with water to which I add the poo and empty it down the culvert in the road – not my favourite job and prone to someone objecting ( I do wash it away well). There must be a better way.


Get your own gravatar by visiting Robin
#9. July 2nd, 2008, at 11:58 PM.

Could you elaborate on the ‘buffer zone’ ? I’ve recently set up one of the green plastic worm farms (separately) for pet waste as my house is on a hill and I’m not comfortable with setting up a digester pit. I set it up with 1 yr old leaf bedding. I’m unsure of the proper layering etc. Also, one article mentioned the ideal temp to kill pathogens for pet waste compost was 164F? I’m assuming the artice was referring to a non vermiculture compost pile. Are there any emzymes etc that could be added to the resulting vermicast to neutralize the pathogens?

Get your own gravatar by visiting Melissa Amlin
#10. July 3rd, 2008, at 12:45 PM.

I want to compost my pet’s waste (2 cats, 2 ferrets & 1 dog) in a seperate composting area – I’m wondering about the “bedding materials” – will I have to add extra bedding materials like cardboard, newspaper, etc. if the cat & ferret wastes are including their litter materials (presently the ferrets use “yesterdays news” and the cats use “swheat scoop”, but if you recommend a better cat litter to use (like the corn ones or something) I could switch them) The yesterday’s news is broken down newspaper already, so would that mostly take care of the bedding needs itself? Would it be too much bedding? Should I be adding some food scraps to this composter as well, or just purely pet waste? How can I deal with the fresh “loads” every day if they need to sit for a while before being introduced to the worms? Please give me some guidance, as I hate the fact that I’m using “enviromentally friendly” litter only to pickle it in plastic in a landfill!!

Get your own gravatar by visiting teri
#11. July 31st, 2009, at 12:58 AM.

I don’t quite understand, I have a vermicomposting bin I use the castings for vegetable garden. I wanted to compost ferret poo and newspaper bedding but unsure about it. he eats only dry ferret pellet type food. so I dont know if he would be considered a carnivore i guess I should look at food ingredients? I don’t know can his poopoo go on my veggie garden? his poopoo that worms have eaten and poopooed into castings? It seems like such a “waste” ha ha. can I put it in?? Thank You

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#12. August 1st, 2009, at 6:29 PM.

That’s a really good question, Teri! Given the fact that it is a pellet food, and it will be well processed by the worms, I would likely be ok with using it myself. No matter what it would get used SOMEWHERE to fertilize SOMETHING!
Don’t ‘waste’ it – but maybe do a bit more research to see if it will be ok for a human-consumption garden.

Get your own gravatar by visiting Melissa Amlin
#13. September 2nd, 2009, at 3:19 AM.

In regards to Teri’s question and your reply – yes, your ferrets are carnivores, or at least they should be, they are actually supposed to be MORE carnivorous than cats. While the pelleted food (aka kibble) probably has a lot of grain/crap/filler in it, as do the many cat & dog food kibbles out there, the diet is supposed to be meat based. I can imagine that the same reasons for concern about using the feces of dogs & cats also applies to ferrets in this case. In fact, if the ferret or dog or cat was fed a purely raw meat diet, their feces would probably decompose and dissolve much easier and quicker and would probably not even need the worms’ help, it’s all the fillers in the kibble that slows things down and makes it more unpleasant to handle.
Anyhoo, so yes ferrets should be included in the probably don’t want to put on your food garden plants.
But I would still like to know about my question about the included bedding???

Get your own gravatar by visiting Edward Murray
#14. September 9th, 2009, at 8:19 AM.

One question and a comment:

I don’t understand why a carnivore’s waste would have more pathogens than a herbivore’s, yet this statement seems to be in every discussion of composting pet wastes. What is the basis for this?

My comment is that mother nature has done a pretty good job of composting the wastes of all animals so why is everyone so uptight about composting pet wastes? You are likely already exposed to any pathogens that your pet has so in one sense, the composted wastes may be safer than sitting down and petting Muffy.

Get your own gravatar by visiting Ashley
#15. October 19th, 2010, at 12:48 AM.

Regarding Edward’s comment that you are already exposed to what your pet has, I have to disagree. You don’t eat things your pet’s poop has touched, and you should be washing your hands after handling their waste. There are a lot of zoonotic pathogens you can get from pet feces, and toxoplasma is the LEAST of your worries. A big one is roundworms. They can cause VERY serious problems, especially in children. (In fact if you have a puppy you need to pick up EVERY one of their poops until they are finished with their series of deworming at the vet.) Hookworm larvae can penetrate your skin. Echinococcus (a tapeworm relative) is another possibility, though less likely in the United States. All of these are shed in feces. Not to mention the regular bacteria like salmonella and such. I don’t remember my parasitology lectures perfectly, but there ARE parasites that can encyst in an infective state and can even survive the heat of forest fires.

As for why you should be more careful with carnivorous pets, I believe it’s because their biology is more similar to humans and therefore we are more likely to be able to share their parasites. Also, their food is slightly more likely to be contaminated since it has meat going into it at some point.

I don’t know a lot about reptiles, but my main worry would be salmonella. Pretty much all reptiles, even pets, carry salmonella without showing any ill effects.

Get your own gravatar by visiting Ashley
#16. May 2nd, 2011, at 6:42 PM.

Given the exact situation you described, with a good monthly preventative and yearly fecal exams, there is probably little risk unless your dog likes to go out and eat other dog or cat poop (mine is horrible about that). Then, your dog could become temporarily infected until the next time you give the monthly dewormer (Interceptor would remove any infection that developed in the past month, not prevent a new infection for the coming month).
For people that don’t get yearly fecal exams and just do the monthly preventatives, I would worry about parasites that exist in cysts and shed at low levels for the dog’s entire life. They don’t cause a clinical problem, and would get killed off each time they try to re-establish, but they would still be in the body and potentially in the feces. If every fecal he has ever had is negative, that’s probably not likely (unless it’s a female and she becomes pregnant, because that can activate some parasites).

Especially when you consider that any feral cats in the area probably consider your nicely tilled garden to be a good litterbox, that’s probably your biggest risk… but that can’t be helped (pregnant women should always wash their hands after gardening because of toxoplasmosis).

Get your own gravatar by visiting Irene
#17. May 11th, 2012, at 3:18 PM.

Hello- I am new to composting and have a question. I live in a apartment and have a small compost bin on my patio outside. Can I add pet waste to my regular compost bin if I do not intend on using the material inside?

Get your own gravatar by visiting Niel
#18. April 11th, 2013, at 11:25 AM.

I refill my cat’s litterbox every day with sand on our plot. then in the morning empty it out and refill . I usually empty it (sand and waste) in one heap. What I want to know is, if i empty it in a spot where there is a lot of sunlight during the day will i be able to use the same sand again in the litter box at a later stage. Should i perhaps spread the sand out a bit or mix it so that the sun can affect the waste more adequately. I am afraid of using the same sand again and that it might still have some diseases from the old waste in it, causing illness for the cats and me.

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