Do Laundry Detergent Packs work in cold water? April 03, 2019 22:48 Updated Our Laundry Detergent Packs are designed to dissolve and work effectively in any water setting. We suggest washing in cold because it saves resources and money! Related articles High-Efficiency (HE) Laundry Detergents What are Optical Brighteners and why does Seventh Generation not use them? How is the concentrated laundry detergent different from the regular laundry detergent? Will Seventh Generation laundry detergent remove perspiration stains? Water temperature and laundry detergent suds.