This is the laziest, most fun test, so let’s start there. Grab a clean, clear plastic bottle—a water bottle works perfectly. Fill it about halfway with tap water.
Now, add five drops of plain liquid dish soap. Don’t use fancy, “moisturizing” stuff; use the cheap, runny kind that looks like water. Cap the bottle and shake it like you’re trying to win a carnival prize—go nuts for ten seconds.
If you get a mountain of fluffy, billowing suds that look like a cloud made of soap, you have soft water. If you get a thin, sad layer of bubbles and the water looks cloudy like skim milk, congratulations—you have hard water. The minerals literally fight the soap and steal its power.
Surprising fact: Hard water can actually save you money on soap because you use less to get clean—but it leaves a film on you that feels like you never rinsed. So, you win some, you lose some, and your hair loses all its shine.
