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'.