White Vinegar is a great thing for a cloth mama to have (I included it on my list of needs for my baby shower). White vinegar is a very mild acid. To mild to harm fabrics. It balances pH levels, removes residues by breaking them down in detergents, softens and fluffs fabrics and disinfects (so good for cleaning out diaper pail and regular household cleaning too). Our mothers and grandmother's know this. Laundry experts know this.
Someone recently said my vinegar advice was bad for synthetic materials in diapers including PUL. This makes no common sense but I dug around and found out I was right. I also dropped the issue with the person since common sense dictates that sometimes that's the wisest choice. Also I used PUL for years and vinegar never had a negative effect.
So if your diapers need a boost in brightness, softness or disinfecting then give white vinegar a try. Usually 1/2 a cup. If you have hard water, vinegar might not be as great as it might cause an odd smell.
If your struggling to rinse all detergent from your diapers add.vinegar to your rinse cycle.
If there is strong urine in your diapers then presoak in vinegar prior to washing (also rinse out overnight diapers and encourage older babies to drink water between nursing) .
There is a great blog post on vinegar (here). I suggest it for further reading. Questions in the comments are also answered.