These can result in an individual losing more water than they are taking in. Kidney function often declines as we age. The kidneys are less able to retain water, which is due in part to the fact that they decrease in mass by between 20 and 25 percent between the ages of 30 and 80. 
Conditions such as incontinence can cause even greater water loss and thus create a greater risk of dehydration.
Additionally, some seniors may decrease their water intake due to fear of incontinence. Studies have shown that the mechanism responsible for the sensation of thirst often declines as we age which means that many older people are often unable to tell when they need to take in fluids.
Signs of Dehydration in the Elderly Dehydration can result in weakness and dizziness, which can increase the risk of an elderly person falling.
Caregivers must be vigilant for signs of dehydration which include:
Decreased or darker colored urine
Lethargy
Constipation
Dizziness
Being irritable
Rapid pulse
Sunken eyes
Muscle cramps
The most important way to combat dehydration is to ensure that they take in water throughout the day even when they do not feel thirsty. Fluids should be offered to them constantly and made readily available by keeping cups of water close to them at all times. Along with water, their preferred beverages should also be supplied. Raw fruit, juice and ice pops may also be used to keep an older individual hydrated. The minimum amount of water an individual needs depends on how much they weigh. A rule of thumb for this is an ounce for every two pounds of body weight.