Traditional tank water heaters. Most water heaters in Southern California are natural gas. In some areas they are powered by electricity or propane. They range in all sizes from point of use to 100 gallons. In a residential home the most common sizes are 30, 40, 50, and 75 gallons. Most water heater installations are about 1-2 hours from start to finish and we can usually replace it the same day. We are committed to providing excellent service by making sure all water heaters are strapped properly and safe for your family or business.