Because the consumer heats several litres of water for 3 to 8 minutes in the shower each time it is used. Across all uses of the bottle, the energy (electricity or gas) to heat this water exceeds what the brand has spent on manufacturing, packaging and transport combined. For rinse-off products, this phase often represents 40 to 70% of the total carbon footprint.
Read the source article: What is the environmental impact of cosmetics?