My gerbils' water bottle is not working!!?

It takes too long to get just a little water out. I bought two brand-new bottles - one gl and one plastic. They both do it and I'm wondering if it's because gerbils don't drink as much as other small animals or if it's because of the dry winter air. I have to take the bottle out of the cage and give it a good vertical shake to get a good volume of water out, but this only lasts for a bit because the spout is dried up when I check it again later in the day. I've even tried loosening the spout where it connects to the bottle. Does anyone know what is going on? Thanks so much!!