Understanding Water Heater Width

Vertical Plumbing
Aug 7
2 min read

Updated: Nov 8

When replacing or installing a water heater, one of the most overlooked measurements is width. The width (or diameter) of your water heater affects whether it will fit in your utility closet, basement, or garage, and can even influence energy efficiency.

If you’re shopping for a new unit or checking if your current one can be replaced with a larger capacity, here’s what you need to know.

Why Water Heater Width Matters

Space Limitations: Some homes have tight water heater closets or alcoves.
Installation Requirements: Manufacturers require clearance around the unit for safety and maintenance.
Capacity vs. Fit: Wider tanks often mean higher capacity, but not always.

Standard Water Heater Widths

Most residential tank water heaters range between:

16 inches – 20 inches for smaller 30–40 gallon units.
20 inches – 26 inches for medium 50–60 gallon units.
28 inches or more for large 75–80 gallon models.

Tankless water heaters are much narrower, often under 15 inches wide, making them ideal for tight spaces.

How to Measure Your Space

Measure the existing tank, from one side to the other, across the widest point.
Check the available space, including room for pipes, insulation, and service access.
Account for clearance, leave at least 2 inches around the unit for airflow and maintenance.

When to Choose a Narrow Model

If your home has a small utility closet, you may need a “short” or “lowboy” model, which is shorter and sometimes narrower than standard units. Tankless water heaters are also a good alternative for limited space.

When to Call a Professional

If your preferred unit won’t fit the current space, a licensed plumber can help with options like relocating the water heater, resizing the plumbing, or upgrading to a tankless system.

Tip: Always check the manufacturer’s installation manual before purchase to confirm the exact dimensions and clearance requirements.