I made a batch of dishwasher soap a few months ago and wanted to give it several tries before making a verdict. I read several reports from people that said homemade dishwasher detergent worked great at first and eventually started to leave a residue, so I wasn’t going to jump to conclusions after my first sparkling batch of plates.
After a couple months of use, I would give it a 97% success rate. This is as good or better than the bargain eco brand I was getting from the grocery store. Occasionally I find a peanut butter knife that didn’t get quite clean or a few spotty glasses, so it might not be as good as the premium brands or gel packs. I’m too cheap to ever buy those, so who knows? Assessing the pros (very inexpensive and probably greener than buying jugs of liquid soap) and cons (having to re-wash a knife now and then), I am going to make another batch!
Living in a city, we have hard water. I’ve read that the effectiveness of these DIY formulas depend greatly on the water and dishwasher that you have, but what is the harm in giving it a shot? Try a half-sized batch to see if it works for you.
I did some extensive searching and this recipe was the most commonly cited and rated positively for hard water. Many people suggest adding 1 Tbs of vinegar to the rinse compartment, but a few mentioned that the vinegar is hard on the seal and that it is better to put a splash of vinegar in a small container on the top rack (measuring cup or tupperware). You can get a combo pack of washing soda and borax from Amazon. I use them both in my laundry soap recipe so I already had them on hand.
Homemade Dishwasher Soap Recipe (visit my Amazon store for easy access to the ingredients)
1 cup borax
1 cup washing soda (not baking soda)
1/2 cup kosher salt
1/4 cup citric acid
Have you had good luck with homemade dishwasher detergent? Any other tips?
June 2014 update:
I read that washing soda converts to baking soda if exposed to moisture. This explains why some people experience cloudier dishes over time. At first I just made half-batches so that I would use them up faster, but now I’ve also started adding little desiccant packs from my vitamins to each jar. This has really helped prevent clumping and is hopefully slowing the conversion to baking soda.