Your white laundry items can often start to have a grey look to them due to a few things. You may live in a hard water area and deposits become fixed to the fibers, or it could just be a build up of detergent within the item. A vinegar rinse is all you need to get your whites white again 

Soak the item in a gallon of warm water water and 8fl oz of white vinegar. Then rinse in a cold water rinse. To keep your white in tip top condition, add about one third of a cup of white vinegar to your rinse cycle, you'll find that your clothes come out brighter and softer. Any vinegar smells should vanish after your clothes have dried.

Another way of getting your whites whiter is using cream of tarter. It is softer on your fabric than bleach which is great for your delicates. Mix 2 teaspoons of cream of tarter in one gallon of hot water and leave to soak overnight.

The following ws send into easyways

A friend of mine gave me this tip. It will also work with light pastel colors. In your washing machine, soak your whites in HOT HOT water with 1 cup of Cascade dish washer soap (power works best) and 1/2 cup of bleach for approx 15 minutes before you set the wash cycle. After soaking, turn machine on to finish the wash cycle. Do not add any detergent. I have used this tip for years. It will get any stain out of your clothes.