What water pressure means
Water pressure is the force of the water in the supply lines, measured in pounds per square inch with a gauge on a hose bibb or test port.
Also called static pressure, PSI.
Where it matters on a plumbing job
High pressure wears out fixtures, valves and water heaters; low pressure makes every fixture weak. A gauge reading takes a minute and belongs on every service ticket.
What the model code says
- Static water pressure may not be greater than 80 psi; above that, a pressure-reducing valve is required. (IRC 2021, Chapter 29)
Check which code edition your building department enforces for water pressure before you quote.
What it costs
The main water line replacement cost guide has the typical job at $1,700 and the usual range at $1,200 to $10,000. The guide shows its sources and what moves the price.
Work it out
- Cost guide: Main water line replacement cost
- Licensing: Plumbing license rules by state
- Tools, templates and guides: Free plumbing resources
Sources: 2021 International Residential Code, Chapter 29, Water Supply and Distribution (ICC). Checked October 9, 2026.