My older parent doesn't drink enough water. What can I do?

If your older parent hardly drinks, don't wait for them to say they are thirsty: with age, thirst often becomes a weaker signal. Instead, build drinks into the day. Offer a glass at set times, keep water within reach of where they sit and sleep, include drinks they enjoy, and check that their pee stays a pale colour, as England's NHS advises. This matters in Thailand: in a study of 704 older people in Bangkok, about 3 in 10 had blood test results showing too little water in the body (8.4%) or were close to it (21.6%). If a doctor has limited how much your parent drinks, follow that advice and ask what to do in hot weather.

For tiredness and poor appetite in hot weather at any age, see Drained and off your food in hot weather? What can I do?

Why do older parents drink less water?

Thirst gets weaker with age

A review by Begg (2017) reports that a reduced feeling of thirst, when the body is short of water, has been seen consistently in older people, and that the hormones that help the body manage water and salt also change with age. A review by Li and colleagues (2023) notes that many older adults do not keep up enough water and that this is often overlooked. In other words, "I'm not thirsty" does not always mean "I've had enough".

Worry about the toilet

The review by Li and colleagues notes that people with bladder leaks may cut down on drinking themselves.

In many homes, other toilet worries play a part too: a parent may drink less to avoid getting up at night, or may find the walk to the toilet hard if it is outside the house or down steps.

Practical reasons

A drink may be out of reach, a bottle may be hard to open, or a parent who lives alone may simply forget. Some parents also say plain water "has no taste".

What have Thai studies found?

What these numbers can and cannot tell us

The Bangkok study measured water balance once with a blood test in one city, and the authors say their way of predicting who is short of water still needs testing elsewhere. It does not show exactly how much any one person should drink. In this study, being 75 or older, having a particular long-term health condition and taking a particular type of regular medicine went with being short of water.

Why medicines and heat matter together

The US CDC explains that older adults do not adjust as well as young people to sudden changes in temperature, and are more likely to take prescription medicines that affect the body's ability to control its temperature or sweat. It is worth asking the doctor or pharmacist whether any of your parent's medicines need extra care in hot weather. Do not stop or change a medicine on your own.

How much should an older parent drink?

England's NHS advises aiming for 6 to 8 cups or glasses of fluid a day. Water, lower-fat milk and lower-sugar drinks, including tea and coffee, all count. The NHS adds that you may need more in a hot environment, when physically active for long periods, or when ill or recovering from illness.

The 6 to 8 glasses is a general guide, not a target for every person. If your parent has a long-term condition, ask their doctor what amount suits them.

How can family help a parent drink more?

Put drinks on a schedule

Link drinks to things that already happen every day: a glass on waking, one with each meal, one with medicines if the doctor or pharmacist agrees, and one in the mid-afternoon. A set routine helps when thirst is not a reliable reminder.

Keep a drink within reach

Leave a glass or a light bottle that is easy to open next to the chair where your parent sits and by the bed. A jug that you fill in the morning also lets you see how much has been drunk by the evening.

Offer drinks they enjoy

The NHS counts lower-fat milk and lower-sugar drinks, including tea and coffee, as part of the daily fluid. Soup, plain soy milk or water with a slice of fruit may be more welcome than plain water. Keep sweet drinks for occasional use. On hot days, the NHS advises avoiding alcohol, caffeine and hot drinks.

Make the toilet easier, not the drinks fewer

If worry about the toilet is the reason, tell the doctor. For bladder leaks, the NHS notes that drinking too much or too little can both make the problem worse, and suggests cutting down on caffeine, found in tea, coffee and cola.

Family can also make the way to the toilet clear and well lit at night. For night-time toilet trips, see Older parents waking up at night: how can family help?

Check in on hot days

The CDC advises family and carers to keep a close eye on older adults during hot weather by visiting them at least twice a day. If you live far away, ask a relative or neighbour who lives nearby to drop in, and also call at set times to ask what your parent has drunk so far. The NHS heatwave advice also suggests checking on anyone at higher risk from the heat, including people aged 65 and over.

What signs should we watch for, and when should we get help?

Signs your parent may not be drinking enough

The NHS lists:

• feeling thirsty
• a headache, or feeling dizzy or light-headed
• dark yellow, strong-smelling pee
• peeing less often than usual
• feeling tired
• a dry mouth, lips and tongue
• sunken eyes

Get an urgent doctor's appointment if

The NHS advises an urgent appointment if your parent:

• feels unusually tired
• feels dizzy when standing up and it does not go away
• has dark yellow pee or is peeing less than normal

The CDC advises seeking medical care straight away for muscle cramps, headaches, nausea or vomiting during hot weather.

Call 1669 straight away if

The NHS advises calling emergency services (1669 in Thailand) if your parent:

• is confused, sleepier than normal or hard to wake
• has difficulty breathing or are taking lots of quick breaths
• has skin, lips or a tongue that look blue, grey, pale or blotchy, or skin that feels cold

If your parent has a long-term condition or a doctor has told them to limit fluids, follow the doctor's advice about how much to drink rather than the general guide above.