part of flock looking sick with purple combs

[Aneury Sanchez]

hello i just wanted some help part of y flock i noticed started getting a purple color in the comb and looking a bit weaker than the rest. They are not coughing or having a hard time breathing is it possible that it could be something in the water. Since i got my flock split in a couple different pens they all get the same food but the main flock gets water from a rain collection barrel so believe it could be something in the water. Will be giving them some vitamin water anyone else have a similar problem happen ?

 

[Eggcessive]

Do you have any pictures? Are they drinking well, and do you have multiple water stations? Is it hot there?