It's enough to make you cross your legs.
Permanently thirsty Sasha Kennedy, 26, says she guzzles as much as six gallons of water and has to go to the toilet up to 40 times a day.
The mother-of-two - who claims she has no health problems - even wakes up several times a night to sip water and go to the toilet.
Sasha said: "If I feel my mouth start to get dry I have to get my next fix of water - it's all I can focus on.
"I feel thirsty pretty much all the time and always have to be sipping water - it's an addictive habit.
"The most sleep I've ever had is about an hour and 15 minutes, because I am getting up to drink or nip to the loo."
By the age of six her mum was placing a plastic jug full of water next to her bed each night.
By the age of 13 she was already drinking up to 15 litres a day.
And by her early 20s she was downing 20 litres a day and her addiction peaked when she began working from home for a telecoms company in 2007.
Sasha said: "I found I was drinking more because I was not self-conscious about going up and getting water in front of colleagues.
"I was drinking about 25 litres a day and my work mates were so concerned they told me to go to hospital and get checked out.
"But they could not find anything wrong. I only start feeling ill if I don't drink - my mouth gets really dry."
Glasgow-based GP Margaret McCartney said the benefits of water are often exaggerated by 'organisations with vested interests' such as bottled water brands.
Writing in the British Medical Journal last year, Dr McCartney said research showed drinking when not thirsty can impair concentration, rather than boost it, and separate evidence suggests that chemicals used for disinfection found in bottled water could be bad for your health.
Drinking excessive amounts can also lead to loss of sleep as people have to get up in the night to go to the toilet, and other studies show it can even cause kidney damage, instead of preventing it.
Dr McCartney also warned that taking on too much water can lead to a rare but potentially fatal condition called hyponatraemia, which sees the body's salt levels drop and can lead to swelling of the brain.
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