My son has worn white pants for I don't know how long now for baseball. I've always pretreated and used bleach with my soap. One thing we were told by a professional team is to use Simple Green. I found it at Wal Mart in the automotive section. Some others have found it by the Windex in household goods. Even though its a concentrate - use it straight and spray it on the pants. Then wash as normal. The ones I've seen washed with that are so white and clean ! I will be trying the next time I wash.