I thought that this might be helpful information for some. Temp. ranging from 14 to 40 the last two weeks. I had not put the heater in my waterer until two days ago. I use a nipple waterer( bucket). I have one in the coop and one outside. The outside one was frozen most days and sometimes it thawed out. The inside on had not froze but the water was cold. I put the aquarium heater in the inside one and took out the outside one. It keeps the waterer around 50 to 60 degrees during the day. Water consumption doubled. Egg size had also decreased a bit and now has rebounded. These layers range from 8 to 10 months old and started laying at about 25 -26 weeks old (Sussex). They are drinking more water because it is warmer. Nothing else has changed.