Ian, i recently had the same thing happen, so the solution was simply to use the word "screwtop" or anything the fits. When included as part of a larger word, the filters are happy. The solution was Fartastic!
You know, i never use that word. My wife doesn't like it.
True story: my son learned to talk at a very early age (words like "apple", though with more of a double 'b' sound, before 12mos and talking full sentences at 18mos). We taught him the word "flatulate". So here we are at my parents home for some holiday dinner. There he is in his little booster seat, using utensils on his own at a holiday meal and not being fed. First he separates all of the food items into little groups not touching one another and then proceeds to eat each group completely before going on to the next group (can you guess where those genes came from!!). A bit later, he 'breaks wind' and this 20month (or 21mo, i'm forgetting) old kid says "Oops, i flatulated badly". My father almost chokes and says "What did the kid say?!!!". My mother, like most Jewish mothers/grandmothers, exclaims with a proud look on her smiling face, "Oh, he's so smart!". I think one has to have some Jewish ancestry to really appreciate my mother's stereotypical response. Anyways, a flatulalistic tale, to be sure.