This past year, I moved into a house where a dog was a resident. Elie. Elie is a fairly large dog, so you can imagine the excrement that might come out of him. I decided to start a pet waste digester. Pet waste can have a negative effect on the environment, by spreading diseases to other pets and wildlife, contaminating water sources, and leaving landmines for others to dodge on sidewalks and in parks.
With about 14 million dogs in Canada, finding a way to divert the approximately 620,000 tonnes of waste rather than throwing the plastic bundles of poop in the garbage to break down anaerobically and contribute to climate change (which let’s face it, already has enough contributors) is a great and easy thing to do! A New Zealand book suggests having a medium-sized dog is twice as environmentally costly as making a Toyota Land Cruiser and driving it for a year.
When walking your dog, you can pick up the waste in a plastic bag then flush it when you get home (not the bag of course), or you can empty it into your pet waste digester, along with your dog’s home poops. A digester allows your pet’s waste to be broken down by bacteria and micro-organisms in a contained area, reducing the harmful pathogens and contaminants, preventing these from being washed into our rivers and lakes, or leeching from landfills and contributing to climate change.
Here’s how you do it: you place a garbage can with the bottom cut off and holes drilled in the sides, in a hole you dig (be sure to call Manitoba Hydro and other utilities for line locating first!), place a layer of rocks at the bottom, add water and test for drainage. You will need to add some septic starter (enzymes and microbes) and water to start the decomposition process, then start adding your pet’s poo and put the lid back on. You should then monitor it and add some water, which also helps with the break down (gives bacteria a nice environment to do their business) and possibly more septic starter every week or as needed. If you aren’t able or willing to make your own system, there are pet waste digesters available to purchase.
Cat feces can also be added, but most websites recommend not adding urine with litter, as it will take a long time to break down. This is likely more applicable to clay based litters, newspaper or corn based litter would likely be fine. I flush my cat’s excrement (I use a flush able corn based litter), so I haven’t added any cat litter yet.
City Farmer states they add pet waste for years before it starts getting full. This depends on how many pets you have, how much septic starter and water you add, and the conditions for your area (digesting stops when it is cold, of course). I just started mine in the Spring, so it is quite empty still. There is no smell and it is not in the way, it is actually quite inconspicuous.
Be sure to place the pet waste digester out of the sun if possible, and as far away from your vegetable crops as possible, as the plants could absorb pathogens if too close. Mine is about 30 feet away from my vegetables. Also, the end product is not like compost from your normal compost system, it will not be safe to use to spread on your gardens. Because pet waste can be quite dangerous to handle, we don’t recommend you handle what comes out of the digester. Once my digester is full, I will likely stop adding pet waste, cover it up, and start a new system, leaving the first digester to ‘finish’ for a few years, then just cover the opening with soil and grass seed. Watch Green Action Centre’s website for an update on the pet waste digester after Winter!
There are detailed instructions available on City Farmer’s website.
A friend is going to help me make one with a salvaged 60 gallon air tank. It will have a lid with a replaceable gasket to help control the smell. If I add septic starter when it’s 1/2 full, how fast and by how much will it break down. My hope is that I will never have to shovel it out.
How many gallons would a Digester have to be for 1 large dog? I live in Alberta Canada where there are several months of winter so nothing will break down during that time. I want to make it big enough that it can build up all winter and break down in the summer. Ideally it would be big enough that I’d never have to empty it. Also how do you ensure it won’t stink.
Great questions! To be honest, we haven’t had any experience ourselves with creating a dog waste digester, but here is a great video to check out https://www.youtube.com/watch?v=if_nHfA93Mk.
From what I’ve read, something the size of a standard garbage bin should be more than sufficient. To ensure it doesn’t stink, drill holes into the sides of the vessel you’re using, and bury it in the soil. The holes allow oxygen to enter the digester, allow soil organisms to enter the digester, and allow water to escape into the surrounding soil. All of these things will reduce odours and are what makes sure the decomposition process happens. It would also be a good idea to ensure you have a lid on the digester to keep odours from escaping and to make sure no animals get in.
To help the decomposition process move more quickly, you can add septic starter to the digester here and there.
Sounds good. I’m planning on making it so the lid fits down tightly and has a rubber seal so it’s almost air tight. Living in town i don’t want the smells to get out. I only have one spot that will work for it so if it ever does fill up I’ll be calling a vac truck to come and suck it out.
To help decomposition would it help to just drill holes in the bottom rather than cutting the bottom right off. Just thinking that would help keep a little more moisture in the container but would still allow drainage.
Over winter I was thinking of adding septic tablets every week or 2 so that it’s there when the temp rises and things start happening.
Make sure you drill holes on the sides of the container, as you actually don’t want it to be air-tight (but it’s totally fine if the lid fits on tightly to prevent any critters from getting in there). Oxygen is required for decomposition to happen because the bacteria and soil organisms that do the decomposition work need oxygen to survive. Without oxygen, you will create an anaerobic (low oxygen) environment, in which decomposition will happen very slowly or not at all, and things will get really smelly. For this same reason, you don’t want moisture pooling at the bottom of the container as this will create anaerobic conditions. Cutting off the bottom wouldn’t cause the material inside the container to dry out, so you wouldn’t have to worry about that.
It sounds like this will be a fun experiment! That’s composting, try something, see if it works out, and if not, try something different. I like your backup plan of calling the septic truck to suck the stuff out if the container does fill up, haha.
So holes are drilled in the sides where the unit is underground? If I smell it when I open it I can handle that, but when closed the smells need to be contained.
You’ve got it! You drill holes in the portion of the container that will be underground.
Holes drilled below the ground surface makes sense to allow worms and air in.
Does it need to have air space in the part that is above ground too? That’s where I could see a lot of stink coming out if there are holes.
Ok. I understand the part that the part sticking out of the ground is sealed and the holes and drainage are in the bottom portion.
In summer I will shovel the poop is as it comes available and over winter it’s usually something I do every few days. In winter I will also be adding quite a bit of snow with every shovel of poop to make sure I add all the “dirty snow” I might also add “yellow snow” to try save part of my lawn, we will see how that works!
By spring I’m sure the tank will be close to full of snow and poop but the level will drop significantly when it melts.
The tank I’m going to use is 20” diameter my 48” long. How much of that 48” should be below the surface of the ground. I can dig a deep hole but I really don’t want to spend more time digging than I have to!
I will put plenty of gravel and broken glass in the hole for drainage and pest control.
Will earthworms or any other bugs make their way into this thing?
I “built” a dog poop digester about a 3 weeks ago. I dug down about 4 -5 feet, used a 5 gallon bucket with a screw top lid. Drilled holes intermittently throughout the sides and the bottom cut out. Added rocks to the bottom of the hole. Then added random stuff like pulled weeds, little bit of grass clippings, some of my neighbors compost, sticks, dog poop, water and compost starter. Didn’t look for the first week, just added poop. 2nd week, of course more poop, but now got myself to look, sniff, etc. No smell – Great! But not breaking down yet; okay, it’s only been a week or so…Since then, I’ve frequently been checking it, adding quite a bit of water, more compost starter, more compost from my neighbor, random yard debris, and of course poop. Well now we’re 3 weeks into it. It doesn’t seem to be breaking down at all. So bought a bottle of “septic system digester.” For true septic systems it says to use 1 cup mixed with water once a month. I’ve added 1 cup twice a few days apart (because it’s getting to a point, where if it doesn’t start breaking down, quick. I’m going to have to reverse the project; and I don’t even want to think about how I’d go about that. Any suggestions would be appreciated. Thanks
You’re sure working hard to make this work! I haven’t tried a digester myself, and would welcome comments from other readers if they have any suggestions. Here are some resources that may help you troubleshoot:
“The Pet Poo Pocket Guide” http://cityfarmer.info/the-pet-poo-pocket-guide/#more-266519
This resource discussing a commercially-available dog waste composter option, which has helpful tips and diagrams that should also apply to a DIY version: https://www.the-compost-gardener.com/doggie-dooley.html
Good luck, and keep us updated on your progress!
– Teresa, composting coordinator
We’re glad you found the information useful, Jennifer! All the best to you and your furry friend.
Great article thank you for sharing! It’s great to see people trying to make positive change to protect the environment
Hi, did you post another article about how it went over the winter months?
Great article! Very informative and helpful. Thanks
Ok so you have surprised me yet again with an article about something that never occurred to me. I like everyone I know who `scoops the poop’ in a respectfully manner for neighbours and community; throw the bag into the garbage. So now you say this is wrong?? OK, if you think of it as protein in a land fill….I guess that is the approach. But even in the article, why use a compostible bag, if you are `flushing’ the waste. I am not sure I understand what it is that is the finished product that you are just covering and leaving in the earth??
Thanks for your comment. We realize that it can be frustrating and confusing to be told different things at different times. Putting the dog waste in a bag and sending it to the landfill is a problem, because even if the bag is compostable, once it gets buried by all the other garbage it will break down anaerobically (without oxygen) which releases carbon dioxide and methane gas (green house gases), among other things. When the waste is left on the grass or sidewalk, nutrients and harmful pathogens can get washed from it to the water table, being released into rivers and lakes (or well water) where it can harm anything that might ingest it. We didn’t say that picking up the dog waste with a bag and throwing it in the garbage was wrong, we just wanted to show that there was a better way to deal with it. Using a compostable bag when flushing the waste would allow the bag to break down quicker in the dump because it would likely be made with more natural materials, unlike plastic bags which take about 1000 years to break down, and even then they only break down into smaller pieces. The finished product is a lot like soil (although we don’t recommend you handle it) and so covering it with soil and planting grass over it will allow the bacteria, insects and microorganisms time to recycle all the nutrients and organic matter back into the earth.
Hope this helps!