PLOT EVENT!!!!!
SO!!!! Here are the facts on what's going to happen starting tonight!!!
As of tonight, the water supply of all major areas populated by wizards will be contaminated with extremely potent aphrodisiacs
The effects of these, naturally, are extreme arousal
Intercourse can alleviate these symptoms somewhat but they return within under an hour after at the latest. Needless to say, good judgment and focus will be greatly affected for those under the influence of the aphrodisiac, so this is prime time for any Tinworth attacks to occur
This probably goes without saying, but Tinworth residents will not be affected (unless they want to be, in which case they just gotta hit up Evan for some of the works for their own private enjoyment)
Does this have to affect your character? Of course not. Maybe they live in an area that got lucky, or they only drink bottled water, or they're traveling, or they live in muggle London and don't generally get their hands on wizarding tap water. There are plenty of ways to get around this plot and participation is entirely voluntary.
Can't think of a way for this to affect your character? Have them visit a restaurant or a friend in Hogsmeade or Diagon. I guarantee you that their water will be affected.