Both work well in Phoenix. Tank units cost less up front ($1,800 to $3,500 installed) and last 8 to 12 years. Tankless costs more ($4,000 to $7,000 installed) but delivers endless hot water and lasts 15 to 20 years. Tankless usually pays back for larger homes or homeowners staying 10+ years.
Upfront cost: what each one actually runs
Pricing varies with your gas line, venting, and electrical setup, but real-world installed numbers in the Phoenix metro tend to land in these ranges:
- Quality 50-gallon tank, like-for-like swap: $1,800 to $3,500 installed
- High-efficiency or hybrid heat-pump tank: $3,000 to $5,000 installed
- Gas tankless, new install with gas line upsize and venting: $4,000 to $7,000 installed
- Gas tankless, like-for-like swap of an existing tankless: $3,500 to $5,500 installed
Lifespan and long-term value
A tank water heater costs less today but you will replace it twice in the time you replace a tankless once. Over a 20-year window, the all-in cost is usually within a few hundred dollars either way, and tankless wins on operating cost because it only heats water when you actually use it. If you are staying in the home long enough to see a second replacement cycle, that math matters.
How each one delivers hot water
A tank pre-heats water and holds it ready. When the tank is full, you get hot water instantly. When demand exceeds the tank (two long showers back to back, or a shower while the washer runs), you get a cold surprise.
A tankless heats water as it flows. You get endless hot water at the rated flow rate, but the unit has to keep up with simultaneous demand. A properly sized tankless handles a typical 4-bedroom Phoenix home easily, an undersized one will limp.
Space, gas line, and venting requirements
Tankless units mount on a wall and free up the closet or garage floor a tank occupied. They also need a larger gas line in most retrofits (3/4-inch is typical for tankless, 1/2-inch may be on the existing tank), stainless steel sealed-combustion venting, and a 120V outlet. None of that is exotic, but it adds to the install if your current setup is not ready for it.
Which one is right for your household
Honest rules of thumb after thousands of installs across the Valley:
- Small to medium home, predictable hot water use, staying under 8 more years: a high-efficiency tank is the smart pick.
- Family of 4+, back-to-back showers, or anyone who has run out of hot water more than once: tankless will fix it and pay back over time.
- Custom home, oversized soaking tub, or whole-home recirculation loop: tankless with a small buffer tank is usually the right answer.
- Tight install budget, water heater in a hard-to-vent location: stick with a tank.