But to me it didnt make sense.
Your reasoning is wrong. You don't
pay for heated water. You pay for heating
the water and that's a big difference. You pay for all
the water supplied and that includes the hot water.
I pay 45,861 m3 for heated water
You pay not for 45 m3 heated water, you pay for heating
that amount of water. I should think the correct term on your bill should be 'podgrzanie wody' rather than 'ciepła woda'. This is the concept you can't understand, maybe because imprecise terms are used on your bill by the administration.
I pay 45,861 m3 + 57.707 m3 for cold water.
They should simply say here you pay for water
rather than for 'cold water'.