Storage Tank Water Heaters
Updated February 20, 2026
Traditional water heaters with insulated tanks that store and heat water continuously. Most common residential option.
Overview
Storage tank water heaters are the standard in most American homes. A 40-80 gallon insulated tank keeps water hot and ready. Gas models heat with a burner underneath; electric models use one or two immersion elements. When you use hot water, cold water enters the bottom and is heated to the thermostat set point. Simple, reliable, affordable, and well-understood by every plumber. The main drawback: standby heat loss (energy spent keeping water hot even when you are not using it) and running out of hot water when demand exceeds tank capacity.
Key Features
- Stores 30-80 gallons of pre-heated water for immediate use
- Gas (natural gas or propane) or electric heating
- Recovery rate: gas heaters recover faster (35-45 GPH) than electric (20-25 GPH)
- T&P (temperature and pressure) relief valve for safety
- Anode rod provides corrosion protection -- the key maintenance item
Sizing & Selection
40-gallon: 1-2 person household. 50-gallon: 2-3 people. 65-80 gallon: 4+ people or homes with high demand (multiple showers, large tub). First-hour rating (FHR) is more useful than tank size -- it tells you how much hot water the heater delivers in the first hour of use. Match FHR to your peak demand hour.
Installation
Gas: requires a gas supply line, venting (atmospheric or power-vent), and condensate drain (high-efficiency models). Electric: requires a 240V dedicated circuit (30 amp for most residential). Both: cold water supply, hot water outlet, T&P valve discharge pipe to within 6 inches of the floor, and drain pan underneath (recommended). Set thermostat to 120 degrees F. Professional installation recommended for gas due to venting requirements.
Maintenance
- Flush the tank annually to remove sediment -- the single most important maintenance task.
- Check and replace the anode rod every 3-5 years. This is what prevents tank corrosion.
- Test the T&P valve annually -- lift the lever, water should discharge and stop when released.
- Insulate the tank with a water heater blanket (-30) if it is in an unconditioned space.
- Average lifespan: 8-12 years with maintenance, 6-8 without. Budget for replacement proactively.
Buying Tips
- Rheem, A.O. Smith, and Bradford White are the three major brands. All are reliable.
- Gas heaters cost less to operate than electric in most areas. Electric is simpler to install and maintain.
- High-efficiency gas models (0.67+ UEF) use power venting and recover faster -- worth the premium.
- A 50-gallon tank is the sweet spot for most 3-4 person households. Going larger adds insurance against running out.
- When replacing, consider upgrading to a heat pump water heater if you have electric -- the energy savings are dramatic and tax credits offset the higher purchase price.