Anglican clergy in the Diocese of Chelmsford have been advised to empty their water stoups, where people bless themselves, until the H1N1 flu pandemic is over.
A number of churches have a stoup for water at the entrance of their buildings where visitors can dip their fingers and sign themselves with the cross of Christ as they enter.
But guidelines on responding responsibly to the H1N1 virus (popularly called 'swine flu') suggest that some caution is now needed.
The Bishop of Chelmsford, the Rt Rev John Gladwin, said the stoups should be emptied for the time being and cleaned out thoroughly.
"The water contained in stoups can easily become a source of infection and a means of rapidly spreading the virus," he explained.
During communion, churches are also being "strongly discouraged" from dipping bread or wafers in the wine (intinction) if the cup has lareday ben received on people's lips, and say administering the elements directly to the tongue may be problematic.
Those who are infected are being asked not to attend church services or meetings. Clergy are being advised against direct pastoral visits to anyone with H1N1 flu - while ensuring appropriate support, concern and prayer.
"Contact by telephone, internet, or other means is to be encouraged," the bishop stressed
He added: "It is not our intention to cause panic, or to exaggerate the seriousness of the situation. The measures [in our guidelines] will assist the churches in providing appropriate support in our congregations and parishes, whilst doing all that we are reasonably able to, to combat the spread of the infection."