Drinking more fluids increases the rate of flushing of bacteria from the bladder.
Drinking an additional three pints of water a day may significantly reduce the risk urinary tract infections in women, a study claims.
Researchers from University of Miami in the US found that women at risk of urinary tract infections (UTIs) who increased their water intake by about three pints every day were nearly half as likely to get UTIs as women who did not.
"While doctors have long assumed this is the case and often recommended that women at risk for UTIs increase their fluid intake, it is never really undergone a prospective trial before," said Thomas M Hooton from University of Miami.
"It is good to know the recommendation is valid, and that drinking water is an easy and safe way to prevent an uncomfortable and annoying infection," Hooton said.
Women are more likely to get UTIs than men in part because the urethra is shorter, meaning it is easier for bacteria to travel from the rectum and vagina to the bladder, researchers said.
Drinking more fluids increases the rate of flushing of bacteria from the bladder and also likely reduces the concentration of bacteria that enter the bladder from the vagina, they said.
This reduces the opportunities for bacteria to attach to cells that line the urinary tract, which is necessary to cause an infection.
The study included 140 healthy premenopausal women who had at least three UTIs in the last year and reported low daily fluid intake.
Half of the women who served as the control group continued their usual daily fluid intake, while the remainder were told to drink 1.5 litres of water a day in addition to their usual daily fluid intake.
After one year, women in the control group had 3.1 UTIs on average, whereas those in the water group had 1.6 UTIs on average, a 48 per cent reduction.
Researchers noted that the water group averaged fewer regimens of antibiotics (1.8) than the limited-water group (3.5), a reduction of 47 per cent.
"If a woman has recurrent UTIs and is looking for a way to reduce her risk, the evidence suggests that if she increases the amount of water she drinks and stays with it, she will likely benefit," Hooton said.