Thanks for the additional information,
First of all, before she is diagnosed, DO NOT restrict water. This can add to the problem and can created additional medical conditions.
It certainly is possible that your puppy has a bladder infection. You will have to have a urinalysis performed to have it diagnosed properly. First, a trip to your vet should rule out the possibility of a urinary tract infection which can cause temporary incontinence- they will need to run a urinalysis to make sure that there is no bacteria, blood, or crystals in the blood and that the specific gravity of the urine (concentration) and pH is within normal range. The urinalysis will also serve as a preliminary screen for other medical conditions that can cause increased urine output such as diabetes, or liver or kidney disease as well. UTI's can cause changes in urination habits such as frequency (during the day) or urgency to go. Tell the vet if there has been any change to the amount of water she has been drinking. Also, try to see if she drips urine while walking and awake. This information can help the vet rule out or confirm a diagnosis.
Assuming the urine is normal and there have been no increase in drinking or urination, you may find that your dog simply cannot hold her bladder. This can be only while sleeping or all day long- the difference being the amount of urine that accumulates while she sleeps. Typically, incontinent dogs "leak" throughout the day- some, only when their bladder is full. As pets age or after they are altered, hormone levels can fall which is why incontinence is found more frequently in older dogs. The hormones help the urinary sphincter constrict- preventing leakage. As the levels fall, they relax- which is predominantly worse when the pet is sleeping and muscles naturally relax some. In many cases, there are medications that can help control incontinence.
I would also mention to the vet that she drinks a fair amount of water. An increase in drinking can indicate a medical condition. Sometimes just an infection can cause an increase while other times it can be an adrenal gland, kidney, or liver issue. Ask the vet what the concentration is. If it is low, Ask the vet to follow up on that. Some of these conditions can go on for years without being detected due to the discreet symptoms.
Here are some links on incontinence you may find useful:
Hope this helps. Please let me know if you need additional information.