Polydipsia (water drinking)

[Dr Lazarus Fraud]

There is a known association between excessive water drinking, for
example in psychogenic polydipsia in schizophrenics, and osteoporosis.
Does anyone know of any research which states how much water is a
dangerous level? For comparison, the normal total fluid intake
(including water) for a sedentary adult in a temperate climate is
about 2 litres per day.