Water Quality - Purple Water

[JohannaPate]

Question about water quality in my granddaughter's chicken coop? Chicken and duck drinking water is turning purple. Water changed every day. Not a mold. Any suggestions? It started turning at the beginning of the summer. Very interesting.

 

[U_Stormcrow]

Is it possible something in it is perfoming a basic pH test? I expect pale purple like that from red cabbage water. Purple like that is roughly 5 - 5.5 pH, which is fine for chickens.