Is it dangerous to drain out more than 1000ml urine at once?

Answer 1

yes it is dangerous if you have more than two liters because if you fell or got hit in the abdominal area your bladder would burst and you would need hospital care immediately. But, this should be unnecessary because your bladder has sensors to tell you when to "go"

Answer 2

It isn't a great thing to flush out so much urine at once. 1000mL is definitely too much to do at once. The kidneys and bladder are at risk of health complications if this much urine is accumulated.