backyard pet waste composter

Last spring I was watching an eco-friendly home improvement show and saw a family install a dog poop composter in the back corner of their yard.  It looked like a quick an easy project, so I did a little research, and found several places where you can get instructions for making one, including a really detailed paper put out by the USDA for Alaskan dog owners.  While maintaining above-ground composting bins with a variety of composting materials seemed extremely complicated, the simpler and more popular versions were below-ground, and essentially created a mini septic tank in your yard.  This is the style I went with.

You might be wondering why anyone would bother making a dog poop composter.  There are a number of ecological reasons to do so: it keeps dog waste out of landfills, allows it to degrade naturally, prevents it from being washed into storm drains to contaminate rivers and lakes, and prevents us from taking a naturally biodegradeable product and wrapping it in plastic so it can never degrade.  Some cities (Seattle for one) don’t allow pet waste in municipal garbage, and there’s too much grit to flush it down the toilet with our waste, so this is a great solution to the problem.  In my case, the fact that I don’t have to carry it from the back yard through my house to the trash can is a plus.  If you just want the waste to have someplace to break down naturally, one poster commented that he had been using the same bin for 10 years and had never needed to empty it.  But it is called a composter, and in my case I would like to be able to use the resulting product to amend our soil, which is clayey silt and not very good for planting.  Every site I went on said to NEVER USE COMPOSTED PET WASTE ON EDIBLE PLANTS.  The microbes in the poop will not be killed, and you don’t want to risk them getting onto any vegetables you will harvest and eat.  However, several of the sites said it is okay to use in flower beds, which is my plan.


plastic garbage can with lid (Most of the directions I saw said to use an old trash can, but I didn’t have any old ones lying around, so I had to go out and buy a new one.  If you can find one that a friend, family member or neighbor doesn’t need anymore, that would be an even more eco-friendly way of doing this.  And I assume you could use a metal can as well as a plastic one, although I would be concerned about the metal rusting away eventually.)

rocks (I used a bag of landscaping river rock)

Rid-X septic tank treatment

Start by digging a hole that will allow your garbage can to sit flush with or just above ground level.  Use your trash can lid to mark the size of the hole to start.  Ideally, you will need a round-nosed shovel to do the digging, but I did not have an ideal situation.  As someone who has dug holes for a living, you would think that I would have all the necessary tools on hand, but T has started driving my car to work due to high fuel prices, and my dig kit was in the trunk, so I had to be creative.  (I’m going to describe my digging process for the sake of my fellow archaeologists who might be amused, but the rest of you can feel free to skip over the next paragraph.)

my tools

First off,  I found a short-handled, flat-nosed spade, which T apparently usually keeps in his truck bed as an emergency snow shovel.  Luckily my pick was in the garage as well, since I was putting the composter in the back portion of the yard, which is intended for RV parking and has a layer of partially-compacted gravel on it.  The flat-nosed shovel would be fairly useless against that.  So I used the pick to get started, and began digging myself a hexagonal hole.  Things went pretty well for the first few feet — I was afraid I would hit pure clay, but our soil is actually fairly silty, with zero gravel in it, and still moist so it cut like butter.  However, at a certain point the handle of my spade was simply too short to comfortably reach the bottom — not to mention the handle kept hitting the sides as I tried to scoop out the soil, a problem that anyone who’s ever dug a 50 x 50 STP is familiar with.  I looked in the garage again and discovered a very narrow, curved shovel the likes of which I’d never seen before.  T said it’s a trench digger, and it was brilliant for cutting the sides of my hole and ensuring I wasn’t angling in, although it automatically bathtubbed the bottom.  The longer handle really helped with leverage, too.  Unfortunately, the narrow blade made trying to bring soil up with it almost impossible — I felt like I was digging with a teaspoon.  I still needed something to bring up loose soil.  I don’t have a sturdy metal dustpan, but as I was headed into the house again I saw something that would do just as well — a sturdy dog bowl.  Using the archaeologist’s time-honored head-in-the-hole dirt-bailing technique, the bowl made pretty quick work of the loose soil in the bottom of my hole.  I had my trash can with me to test the depth of the hole as I worked, and when I got close to deep enough, I used a few hand tools to make sure I had square corners and a nice, even bottom.  My favorite hand digging tool, my rock hammer, was in my car, but I figured the claws on a regular hammer would work.  They did an okay job, along with some scraping from a little three-pronged hand fork I had laying around.  I’m sure I could have had uneven sides and an irregular bottom, but you know, old habits die hard.

Once I had an appropriately-sized hole, I needed to make some modifications to my trash can.  In order to allow for drainage into the surrounding subsoil, I needed to cut out the bottom of my can, and make several holes in the sides.  I actually cut out the bottom first, but I would recommend putting the holes in the sides first, since the rigidity of the can is compromised once the bottom is out.  But this is what I did.

I discovered just as I was about to start this portion of the project that T’s drill was missing.  Turns out, he loaned it to a friend.  In my case, I used an awl to make a hole for the keyhole saw to start, but a drill would be quicker and easier.  With the can upside-down, I had to stand on the rim to keep it from moving while I cut, which was a two-handed process for me.  Having someone else around to hold onto the can might have been easier, too.  Getting around the two insets was probably the most difficult part, but the whole process took less than 5 minutes.

bottom off!

The next step was to put holes in the sides, which could be done quickly and easily with a drill, especially if the base is still intact to keep the sides rigid.  Most of the directions I saw said to put in about a dozen holes, and weren’t more specific than that.  I’m sure you could put in a lot more holes of you wanted, it would only increase drainage, which can’t be a bad thing.  I decided to keep my holes near the bottom, in the belief that any liquefied poo would tend to flow downwards, and having holes up high probably wouldn’t do much good.  I could have just waited until T had his drill back, but I was being stubborn, and since I had triumphed over a lack of proper digging tools through creative problem solving, I felt like I needed to keep going here.  So I replaced a drill with these:

drill replacements

I used the awl to make starting holes at the corners of small triangles, use the keyhole saw again to cut two of the sides, and then (because it was easier than finishing the third side with the saw) used a pair of pruning shears to clip the third side of the triangle.  I had to stick my knee into the can to brace it, and be very careful not to saw into my own leg.  Really kids, take my advice, make sure you have a drill on hand and put the holes in before you cut out the base.  This was an unnecessary pain in the butt.

my ragged triangular drainage holes

 The next step was to get the can outside and into the hole I’d dug.  In order to help with drainage, most directions say to put rock/s in the bottom.  I assume that any kind of gravel, baserock, river rock, or even some larger stones you have hanging around would work, but again, I had to go buy rock to fill the bottom of my composter.  One small bag was just enough to come to the bottom row of holes.

interior of composter

There was a gap between the sides of the trash can and the sides of my hole, so I poured some of the backdirt in to fill the space a little bit.  Now all that my composter needed was, well, something to compost.  So I cleaned up the yard and threw everything in.  I know you don’t need a picture of that, so instead, here is a picture of the source instead.

the dogs “helped” from afar

Once the poop was in the composter, there were two more ingredients necessary to get my mini septic tank working: water, and septic enzymes.  I sprinkled the Rid-X over the top, just enough to coat everything in a thin layer, and then poured in a few gallons of water.  I figured, if the directions said to use half a box for a true septic tank, I could use a lot less for a system as small as this one.  And then the can lid went on.

UPDATE: I realized that people are still viewing this post on a regular basis, and I would like to provide my long-term results with this project. We live in an area with clay soils. Therefore, I could never get this septic system to work quite correctly. I don’t think I had anywhere near enough holes in the plastic sides of the trash can, and I probably should have made sure there was a thick layer of gravel below the barrel to help with drainage. In the summer, it also gets very hot here and this was out in full sun, so keeping the system wet may also have been an issue. For about I year I would do my weekly yard cleanup, dump it in, add a few buckets of water (usually enough to just cover the…deposits), and a sprinkle of Rid-X. By the end of the year, the bucket was almost full. I let it sit over the winter (without keeping up on water/Rid-X since it was below freezing) to see if it would decompose a bit more, but there wasn’t much more room come spring. I tried again during the first few months of the second year, and pretty quickly got to the top of the can. Since then, I have just let it sit, covered, in the back corner of the yard. I am pretty sure that black widows have moved in under the domed lid, and the weeds back there are quite lush. It isn’t safe to use composted dog waste on food, and with a young daughter I haven’t felt safe using it in my flower beds either. So while I was excited about this going in, and it was a very convenient disposal site during the first year, I never got it to work as a self-sustaining system.