lukewarm, tepid, or not hot enough

[optimistic pessimist]

Hi all.

I took a lukewarm bath last night. That's why I caught a cold.

I took a tepid bath last night. That's why I caught a cold.
I took a bath that wasn't hot enough. That's why I caught a cold.

I know the opposite of hot is cold, but if I use it, it's different from what I want to say.​

Among the three sentences which one is a common phrasing? Or is there another way to say this?

OP

 

[Rover_KE]

None of those statements is common—you don't catch a cold by taking lukewarm/tepid baths.

There's not much to choose between lukewarm water and tepid water, but in real life I think most people commonly say 'The water wasn't hot enough'.

 

[GoesStation]

Of the three, tepid is far less common in American English. The other two ways of expressing temperature are common.