Key takeaways
- Pressure at the fixtures depends on flow capacity, and flow capacity depends on pipe diameter, length and material.
- A long run loses more pressure to friction; the longer the line, the stronger the case for the next size up.
- The meter and the utility's tap set the ceiling; a bigger private line can't deliver more than the meter passes.
- A separate irrigation line often makes more sense than upsizing the house line.
Diameter, length and friction
Water moving through a pipe loses pressure to friction against the pipe wall, and the loss grows with length and with flow rate and shrinks with diameter. A short line on a city lot in Bremerton barely notices; a 400-foot run to a Kingston or Bainbridge home notices a lot, and a 600-foot well line in Seabeck notices more. That's why the same house can have fine pressure on one lot and poor pressure on another with the same utility and the same fixtures.
What most homes need
A typical single-family home with a standard meter is well served by a one-inch service line in HDPE or PEX, and that's what most replacements are. Older homes often had three-quarter-inch galvanized, which was marginal when new and is badly restricted now; going to one inch on the replacement is a noticeable improvement by itself. Larger homes, long runs, multiple bathrooms running at once, and homes with a shop or an ADU on the same feed are the cases where an inch and a quarter earns its cost.
The meter is the ceiling
The utility's meter and the tap on the main set the maximum flow. A larger private line behind a standard meter doesn't deliver more than the meter passes; it only reduces friction loss on the private side. If the goal is more total flow, the conversation includes the utility and a larger meter, which usually means a larger fee and sometimes a larger tap. We'll tell you when that's the real limit.
Irrigation and outbuildings
Irrigation is the usual reason a house line feels undersized: a zone running while someone showers. Rather than upsizing the house feed, a separate irrigation line from a point near the meter, or on a well from the pressure tank, keeps the two from competing and makes irrigation leaks easier to isolate. A shop or barn at the far end of the property is the same logic.
Written by the crew at 360 Leak Finders
We locate, excavate and repair buried water lines and exterior drains across Kitsap County, 24 hours a day. If this guide raised a question about your property, call (206) 354-9906.