Bath Mats Tests How Do I Get A Sample Of My Water Tested?

How do I get a sample of my water tested? - bath mats tests

I drink lots of water and when I let go of my tap water in a glass bottle or more than one hours tastes really bad, so the bottom of the mat is always dark in my bathroom discusting mold. How do I get my water tested to see what's inside? I do not know if that helps at all, but I live in an apartment complex, and I did not hear my neighbors say the same things on the carpet bathrooms.