Is it possible to drink too much water if you drink to thirst?

Hello all

I am at the end of day 3 of my water fast. I am drinking to thirst, and have drunk 3 litres or 3 quarts of water today. I have lymphatic congestion and I am thinking that this might be the cause of so much thirst.

Is it dangerous to drink too much water? Would over 3 litres / quarts be OK? I have read about straining the kidneys or causing brain swelling if one has drunk too much water, especially on fasts.

Is there a point beyond which one should not drink to thirst? To me it seems logical to drink to thirst, but as a precaution, even though it is purely theoretical and not coming from listening to the body, I am avoiding going over 3.5 litres a day.

Everytime I drink water I can feel the lymph moving around my eyes, which is where much of the congestion is. So it seems that so far the water is only doing me good.

Thanks.