A 40-gallon water heater is a popular option for homeowners because it provides plenty of hot water for most households. It's important to size the water heater correctly to ensure you're getting enough hot water and to avoid running out of hot water during peak demand times. A 40-gallon water heater is typically 24 inches wide, 33 inches tall, and 18 inches deep. It weighs about 165 pounds when full. The storage tank on a 40-gallon water heater is about 10 gallons, so it can provide about 34 minutes of continuous hot water at 130 degrees Fahrenheit. If you're looking for a new water heater, be sure to consider the size and how it will fit in your home. A 40-gallon water heater is a good option for most households, but you may need a larger or smaller size depending on your needs. If you're not sure what size water heater you need, consult with a plumbing expert to help you choose the right size and model for your home.