With all the dirt and goo on her hands, Kat needed a place to wash and clean. You know hygiene was an important thing to the Slytherin and she would never want to wait any longer for the germs to spread. Take about ew, you know. She needed to pay a visit to a bathroom, and now that she was a student leader Kat decided to visit the prefects' bathroom.

Hehe. SHIFTY.

... Oh, so this was how the prefects' bathroom looked like. Hmm, it was cool.

Anyway, she needed to collect the last ingredient. Taking out an empty bottle from her slingbag, Kat turned the faucet on and let the water drip for a while. First, she washed her hands thoroughly so that all the dirtiness was gone. The next, she took the empty bottle and filled it with water. Maybe at least 3/4 of the bottle was filled with water before Kat recapped it and turned the faucet off. Okay, her fourth ingredient was collect and she was done.

Her last destination? The potions classroom.