Q: How much water should by guinea pigbe drinking?

Hi, about a month ago one of my guinea pigss died (we believe it was due to stones) I noticed that before she had died I was refilling a 20 oz water bottle every morning, and whenever she would squeak, nothing I gave her would stop her. Then she died. Now a month later, my other piggie is drinking a little more then normal, and when she squeaked a few minutes ago, she had plenty of hay, water, and food. Now I'm afraid that the cycle is starting again. ISs this normal?