When a hamster doesn't have a water dispenser, you can provide water for it through the following methods:

Use Shallow Containers as a Substitute
Select shallow containers such as small bowls, saucers, or the bottoms of disposable cups, and place them beside the food bowl in the cage. Change the water 1-2 times a day to reduce the risk of contamination. Pay attention to the height of the container to prevent the hamster from getting its fur wet or knocking it over.
Make a Simple Homemade Watering Device
Fix a mineral water bottle cap inside the cage, or use a straw to press and drip water for the hamster.
Use the bottom of a cut-down paper cup or plastic bottle as a temporary water trough and fix it at a lower position in the cage.
Supplement Water through Food
Feed fruits and vegetables with high water content (such as cucumbers, apples, and cabbages), but control the amount to avoid diarrhea. Note: This method cannot completely replace drinking water, and clean drinking water still needs to be provided.
Train the Hamster to Use a Ball-Tipped Water Bottle
If you buy a water bottle temporarily, you can use food to guide the hamster to learn to lick the ball to get water. This method is more in line with the hamster's habit of using a specialized water dispenser.
Important Tips:
It is preferred to use cooled boiled water or purified water to avoid diarrhea caused by tap water.
Clean the water container and wet bedding every day to prevent wet tail disease.
It is recommended to buy a specialized water dispenser in the long run to avoid potential health risks caused by temporary solutions.