What is the minimum size of the water service from the property line to the water heater?

• A. 1/2 inch
• B. 3/4 inch
• C. 1 inch
• D. 1 1/4 inch

Answer: (B)

The main idea is that the service size from the street into the building sets the maximum amount of water that can flow to meet demand. For a typical residential installation, the minimum size is 3/4 inch. A 3/4‑inch service provides enough cross‑sectional area to keep pressure up and supply the hot water needs without bottlenecking when multiple fixtures demand water. A 1/2 inch line would become a choke point, causing low flow and longer waits for hot water. Larger sizes, like 1 inch or 1 1/4 inch, aren’t required for standard homes and add unnecessary cost unless there’s unusually high demand or a long run to the house. So, 3/4 inch is the minimum residential service size.