A quick Google search provides several pages that suggest drinking tea can lead to kidney stones.
Avoid drinking too much tea or coffee.
The consensus theory seems to be that oxalate and other minerals in tea form salts crystals in the urinary system (stones).
However, the Mayo Clinic reports:
Drinking a cup of black tea or green tea each day could reduce the risk of kidney stones. One study in women found those that drank the most black tea had a slightly lower risk of kidney stones. The study was not rigorous and only involved women, so it doesn't provide strong evidence that drinking tea is helpful for all kidney stones. If you enjoy drinking tea, there may be a chance that continuing to drink tea can help reduce your risk of kidney stones. However, tea contains high oxalate levels. So if your urine has a high oxalate level, your doctor may advise against drinking tea.
Does drinking too much tea cause kidney stones?