COPIED FROM CDCL WEBSITE:
Recently at a Nuneaton Club match a member of staff there spotted a visiting player (not one of ours) who had a drink not bought on the premises. You are reminded that all the venues we use expect you to buy your drinks while there rather than bringing them along with you.
Some chess clubs have in the past been required to change venue because of this happening and also because, frankly, chess players don't buy a lot at the bar even when they are buying all their drinks there. We are not the most profitable sort of club to host.
Even bringing your own water/soft drinks into the venue could be considered a problem so please don't do it. We have some very supportive venues and we need to support them. Your active co-operation is required. Thanks.
(Posted on behalf of Mike Johnson - wording is mine rather than his).