How do you measure water inlet size?

Author: River Aufderhar  |  Last update: Sunday, November 30, 2025

Measure the Outside Diameter (OD) of your pipe or pipe fitting:
  1. Wrap a string around the pipe.
  2. Mark the point where the string touches together.
  3. Use a ruler or measuring tape to find the length between the tip of the string and the mark you made (circumference)
  4. Divide the circumference by 3.14159.

How do you measure inlet pipe size?

To find it, measure around the circumference of the pipe with flexible measuring tape. Divide the circumference by pi, or about 3.14159. For example, if the circumference is 12.57 inches (319 mm), you would divide by pi, and get an outside diameter of about 4 inches (100 mm).

How to measure the diameter of a water supply line?

Using a Soft Measuring Tape

Measure the pipe's circumference by wrapping a soft tape measure around its outside circumference. Divide the circumference measurement by pi (3.1415) to get the outside diameter.

What size is a water supply inlet?

The water service line for a residential home is typically a ¾” to 1” pipe that can be seen entering your building near the water meter.

What is an inlet size?

The inlet size is the interface or the size/type of the threads where you attach the valve.

Measuring Size Of Pipe & Pipe Sizing Chart

How do you find a water inlet?

If your home has a basement or crawlspace, check there first. For homes built on a slab, check in the garage or near your water heater. The incoming water line usually comes through the foundation near the front side of your house. Follow this line up to the water meter.

How to measure water supply line fitting?

Measure the Outside Diameter (OD) of your pipe or pipe fitting:
  1. Wrap a string around the pipe.
  2. Mark the point where the string touches together.
  3. Use a ruler or measuring tape to find the length between the tip of the string and the mark you made (circumference)
  4. Divide the circumference by 3.14159.

How is water supply measured?

The most common units are centum cubic feet (CCF) and the gallon. A CCF also called an HCF (hundred cubic feet), represents one hundred cubic feet of water. The first "C" comes from the Roman word for hundred, "centum.” This is the most common unit used by both water and natural gas utilities.

What is the average water line diameter?

The most common pipe diameter for water mains is 6 to 16 inches, with 8, 10, and 12 inches also being used. Branch lines providing service to individual homes, offices, buildings, and businesses vary in size from as small as half an inch in diameter up to 6 inches.

What size is exterior water line?

These water lines typically range in size from 3/4” to 4″ in diameter, and are connected to the main supply line. Faucets and valves control the water flow for each plumbing fixture. The main line immediately leads to water ready for cold water use.

Is pex safe for drinking water?

Is PEX safe for drinking water? Yes, our PEX-a and PEX-b are both safe for drinking water. Our piping system solutions are all third-party tested through IAPMO or NSF to the following standards: NSF/ANSI 61 drinking water systems components - health effects.

How do you tell what size fitting you need?

What size thread should I get for fitting? Measure the inside diameter (ID) of the female thread and the outside diameter of the male thread (OD). This number will be used to figure out the size of the thread. To find the nominal size, count the threads on a fitting and look at the thread chart earlier in this guide.

How do you calculate inlet?

Inlet Capacity Formula

To calculate inlet capacity, multiply the orifice flow coefficient by the area, then multiply the result by the square root of the product of 2 times g times the head.

Do plumbers use inside or outside diameter?

The outside diameter is an important measurement because it's used to determine the size and compatibility of pipes and their associated fittings, connectors and components across various plumbing applications.

How is water intake measured?

Weight-based Water Intake

The general rule is to drink one ounce of water for every two pounds of body weight. All you have to do is weigh yourself, then divide the number of pounds by two to figure out your needed water intake.

How much space does 1 gallon of water take up?

1 US gallon = 0.1337 cubic feet = 3.79 liters. 1 Million gallons = 3.07 acre-feet = 1.547 cfs per day.

What does a water meter look like on a house?

There are two basic types of water meter registers -- the straight-reading meter that resembles an odometer in a car, and the round-reading meter that has several separate dials. The meters measure water in cubic feet (one cubic foot equals about 7.5 gallons).

How do I tell what size my water line is?

First, find a piece of string. After that, wrap the string around the pipe and mark the point where the string crosses. The length between the marks gives you the pipe size.

How to calculate water supply pipe size?

Choose a suitable water velocity based on material, pressure, and application (typically 3-8 feet per second). Use the formula: Flow Rate (GPM) = Pipe Area (square inches) x Velocity (ft/sec). Calculate the pipe diameter based on the desired flow rate and chosen velocity.

What size water line from street to house?

For most single-family houses, a 1” water service line is more than large enough to provide the necessary amount of water. Sometimes, older homes will have smaller water lines.

What is an example of a water inlet?

An inlet is a (usually long and narrow) indentation of a shoreline, such as a small arm, cove, bay, sound, fjord, lagoon or marsh, that leads to an enclosed larger body of water such as a lake, estuary, gulf or marginal sea.

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