According to WebMD, water blisters on the hands are usually caused by repeated friction, such as using a rake without wearing gloves. Although water blisters are usually harmless, a doctor should be seen in some cases.
Water blisters are bumps filled with a clear fluid called serum. They can range in size and resemble a bubble on the hand.
Other possible causes of water blisters include electric, radiation or chemical burns, exposure to freezing temperatures, spider bites and infection. Water blisters caused by friction can usually be treated at home. If there are other symptoms, such as a fever, swelling or a possible allergic reaction, see a doctor right away.
Home treatment for water blisters is to protect the blister with a loose bandage. Avoid the activity that caused it to form.