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Urinating while sleeping can be from a loss of sphincter tone when they are relaxed. Many times this is a hormonally responsive issure and can be managed with medication. The drinking more water is a concern as well. She may have an urinary tract infection and that is what is causing the accidents.
In any case, you need to get her into the vet tomorrow. They will run bloodwork and an urinalysis to make sure kidney function is okay and see if there is protein or blood in the urine. With the results they will be able to diagnose and give you the appropriate medication.