TVC dipslides are an indication of microbial activity. They are a good first step in empowering dental teams to proactively monitor water quality, providing:

a) there is a wider procedural system to support positive (false) readings, for example  with a UKAS water lab

b) the user is aware they can produce false positive and double negative readings. This  can be caused by various external factors causing raised temperatures, which in turn affect the results: examples include hot weather, heat from other equipment (fans, heaters etc) or non-visible factors like warm air ducts.

Red smears or streaks on dipslides can be caused by false positives from raised water or air temperatures