I found this article on the Hartford Courant website: Too little calcium, water linked to kidney stones.
Researchers in a study tracked 78,000 women in their 50s and 70s to find links to kidney stones. They found that women who got more calcium in their diet (in their food, not from supplements), drank more water, and consumed less salt had a lower risk of developing kidney stones.
Doctors used to think that kidney stones came from getting too much calcium but have now learned differently. It isn’t too much calcium, it’s whether your body uses the calcium or eliminates it. Calcium in your diet is more readily used than calcium from supplements. Other vitamins and minerals, like vitamin D, help the body to make better use of calcium.
Increased salt in your diet can increase the risk of kidney stones because sodium causes the body to eliminate calcium through the kidneys. The phosphorus in some soft drinks and other foods can also prevent the body from absorbing calcium causing more of it to pass through the kidneys.
Finally, increased water can help because larger amounts of fluids passing through the kidneys dilutes the crystal-forming minerals making it less likely that stones will be able to form.
My Mom has been in the hospital two or three times with kidney stones and her primary issue is that she doesn’t drink enough water. It can be difficult for people to drink enough water. It doesn’t taste good from the faucet because of chlorine. Bottled water is expensive when you are away from home. My Mom got a good water filter at home and takes her water with her when she is away from home.