growing up, my mom always washed our clothes by washing whites separately from darks. that made sense and i always do that. however, i notice that sometimes my clothes aren't as bright or the material starts to pill or clothes still gets discolored. for a couple of years now, i've begun separating out my clothes and washing them according to the tag. it is a bit time consuming and can seem wasteful, but as long as you adjust your load so that you aren't using a ton of water for small loads, your water consumption should not increase tremendously.
by following the directions and washing our clothes this way, i've noticed that they are looking better and lasting longer. i found this guide "how to read a laundry tag" extremely helpful when trying to decipher all the symbols on the tags. i'm keeping a copy in our laundry room for easy reference!
-kaolee
