Time to water the plants? As your morning shower heats up, let the water fill a watering can with the cold water. Wait for the water come to room temperature, and give your thirsty plants a soaking. (Plants prefer tepid water to bone-chilling H20.) What's that? You don't have a houseplant? Then go pick one up! Plants help purify the air in your home by filtering out toxins. Foolproof, hard-to-kill varieties include the spider plant and succulents.