Time to water the plants? As your morning shower heats up, fill a watering can with the cold water before it goes down the drain. Let the water come to room temperature and give your thirsty plants a soaking (plants prefer tepid water to bone-chilling cold H2O). What's that, you don't have a houseplant? Then go pick one up -- it can help purify the air in your home by filtering out toxins. Foolproof, hard-to-kill varieties include the spider plant and succulents.