It sounds like you have a sanitation problem. Clove flavors (derived from a compound known as 4 vinyl guaiacol, 4VG for short) are produced by POV positive beer yeasts (e.g. Belgian Abbey and German Weizen yeasts), by some wine yeasts, and by most wild yeasts. The latter are most likely your problem.
However, not all such flavors are really clove flavors. If ...
To eliminate chloramine (as distinct from chlorine), your water apparently needs to be boiled for a minimum of 20 minutes. Alternatively, you can use the chemical method - Campden tablet(s) - sodium metabisulphite. This latter method works for me, but just make sure you don't overdose - one tablet per 10 gallons is a guideline.
Clove-ey flavor in my experience is due to
Yeast health (namely- hot fermentations)
Chloramines in water
My prime bet is fermentation temps- you say you ferment at 66-68F - is this ambient temp- or temp controlled? Are you pitching your yeast when your wort is hot? I would discount an infection (#3) if the clove doesn't develop to ...
Do you know when the clove flavor gets into the beer? I'd try the wort pre boil, post boil, and then the beer right after fermentation.
That said, a quick web search suggests this off-flavor as phenolic. Clove is on the harmless end of this off-flavor; I had beer that tasted medicinal and like plastic. This can depend on what the water supplier puts in the ...