1. Vinegar
You can add regular ol' white vinegar to a load of whites (about half a cup) to help keep them looking their best. Or, you can apply it directly to stains before throwing your clothes in the washing machine. Try it on pit stains or the collar that are starting to yellow, and watch it work it's magic. Worried your laundry will smell like vinegar? Don't be. As it dries the vinegar smell goes away anyway.
2. Lemon Juice
Just like with the vinegar, you can add a half a cup of lemon juice to your load of whites (yeah, separating your loads by color will help keep your whites looking sharp, too). You can also use hot water with lemons as a pre-soaking option. Boil a pot of water and add a bunch of lemon slices to it. Then, drop in the clothes and let sit, minimum about an hour, or if you really want some extra power you can let them soak overnight.
3. Baking soda
Baking soda comes up a lot in DIY non-toxic cleaning. If you have a stain in a white shirt, trying mixing baking soda with a bit of water to make a paste and rub that on the stain. You can also add half a cup of baking soda to your normal laundry load and it will help whiten, freshen, and even soften your laundry. Sounds like a wonder product! And, when is the last time you made it to the bottom of a box of baking soda anyway - I never have. Use it up in your laundry, then when you spring for a new box to make a fresh batch of chocolate chip cookies, you'll be surprised how springy your cookies are with non-expired baking soda.
4. Hydrogen peroxide
Okay, this one might not be in your kitchen, but it's probably in your medicine cabinet. That's still pretty close, and it can work wonders on whites. Basically, hydrogen peroxide is a non-chlorine bleach. This means, you should still be careful with it around clothes that aren't white, but for ones that are, if the other things on the list aren't working, give this a shot before reaching for your standard chlorine bleach. Add half a cup to your normal laundry detergent to brighten and whiten.
5. Sunlight
This one is by far the easiest. It's as simple as letting your clothes dry outside in the sun. This won't work on stains from spills, but it will help keep your whites bright (instead of dingy) the more you wash them. You know how when you leave stuff outside in the sun for a while it starts to fade (as if you bleached it), that's the premise here. The sun is pretty powerful, meaning it will dry your clothes effectively without using any energy and it will help keep those whites nice and pearly bright.
And, don't forget to check out our roundup of safe laundry detergents, so that you aren't adding any unnecessary chemicals when you put the shirt in the washing machine.
Resources
(1) https://oem.bmj.com/content/72/11/757
https://www.apartmenttherapy.com/how-to-whiten-laundry-without-chlorine-bleach-109590
http://www.onegreenplanet.org/lifestyle/whiten-whites-without-chlorine-bleach/
https://www.dropps.com/blogs/spincycle/15014849-get-your-whites-whiter-without-bleach
https://www.rd.com/home/cleaning-organizing/how-to-whiten-clothes-without-using-bleach/