The conundrum of the woman whose nausea and sickness resolved on a visit to France, and ceased altogether on switching to drinking only bottled water, appears to have been resolved.

Prompted by the suggestion from retired engineer Derek Jones, mentioned in this column, that she request Thames Water to investigate the matter, she reports it found a high concentration of the bacterium E.coli in the tap attachment of her kitchen sink. Since sterilising it, as advised, she has returned to drinking tap water with no further problems.

It is of interest that United Utilities (which supplies water to seven million people in the North West) observes in its “Caring for water in your home” that “taps may become contaminated from food or other items washed in the sink or from dishcloths left to dry”. They recommend cleaning them with a mild household disinfectant.

Several people have queried the alternative hypothesis that fluoride (whether natural or artificially added) present in the water supply at a concentration of just one part per million might be responsible for otherwise unexplained stomach complaints. This would seem improbable, though specialists at the All India Medical Institute report that fluoride levels in the blood were “significantly higher” in those with non-ulcer dyspepsia compared to those measured against the control group.

“Chronic exposure should be considered in patients where other possible causes of dyspepsia have been excluded,” they write (I P Gupta et al, Journal of Gastroenterology and Hepatology, 1992, vol. 7, pp 355-9).

This is an excerpt from the “Doctor’s Diary” column