# What is the density of water?

one gram per milliliter ( $c {m}^{3}$) at STP
The mass unit of the metric system was defined as the mass of one $c {m}^{3}$. This definition connects the basic units of mass, volume and distance in the metric system ( brilliant)
As 1 gram of water occupies one ml ($1 c {m}^{3}$) , the density of water is $1 \frac{g}{m l}$