If you'd like to download my version, you can do so here. Here are some examples from my log.
What you'll find in the document:
Date: the date you threw away the item(s), you could also add a column to show when you bought it/made it to see how long it was sitting around before you tossed it
Items: The item(s) in question that were thrown out
Quantity: Number or rough amount works, this will help determine how much money you wasted. Even better if you have some sense of how many you threw away in relation to how many you bought.
Cost: If you know the exact cost of that bag of rolls (for example), let's say that was $4.50, and there were originally 8 in the bag, and you threw away 3, then you can set up a pretty easy formula to calculate exactly how much money you wasted. If you got something for free, then of course the waste amount is $0. Or you can approximate the cost of an entire meal and then calculate roughly how much of that meal became leftovers and therefore how much money was wasted.
Why Thrown Out: Mine are generally mold related because it just sat around too long in the open, or dried out/withered would be another frequent one for me because it didn't get used. However this could also be because it was accidentally dropped on the floor or your kid mashed it into a goopy mess, etc. Or the expiration date has passed (not the best by date, those are just made up numbers to sell more groceries).
How to Improve: The idea here is to get you to think about why something was wasted and brainstorm ways to avoid that waste in the future. Not everything is going to have an easy answer. You can't be less clumsy (although you can probably try to take your time and grab something properly), you can't make your infant do... well really anything. However, you can try to freeze things when you buy it. For example, bread, I just throw in the freezer now as a whole loaf and then pull out pieces straight out of the bag to throw in the toaster. Or ginger, I like to grate up everything I buy all at once, and freeze the grated ginger by the tablespoon so I have it on hand when I need it. Leftover coconut milk or tomato paste, when I only use a portion of a can, gets frozen by the tablespoon as well. Taking things out of plastic bags so the moisture doesn't make them spoil faster, or not storing other fruit near your apples, which will ripen them more quickly, also helps.
So what's the point of a waste log?
Well, one is to save money. If you can quickly and easily see why you are wasting money and how much, then you can change your behavior. For example, instead of buying that net of 10 lemons for $4 because the by the each price is so much lower, when you really only needed one, which would have cost you $1, but then you threw out 9 of those lemons. It would have been far cheaper to just buy that one lemon. So then next time you just buy that single lemon, unless you know for sure you'll be able to process and freeze the other 9 before they go bad.
Another is to get you thinking about what and why you throw things away and get you thinking about how to improve that behavior in the future. Blah, blah, starving orphans in Africa (but really starving people everywhere). All of that waste has to go somewhere too and you're using up resources that could be better used elsewhere. By reducing your waste, you are lowering your environmental footprint.
Improving your health is another one (I'm not a medical professional, so take this with a grain of salt). Eating rotten/moldy stuff is bad for you, it leads to fun things like food poisoning. Sometimes it's really hard to tell if something has gone bad (or easy to miss a small spot of mold), so by reducing the chances of something going bad, you're decreasing the likelihood that you'll accidentally eat something that has started to rot or mold, thereby also decreasing the likelihood of getting food poisoning.
