Sizing Guide
How to determine the right PlumBuddy Valve size for your home's water line, including pipe compatibility and reducing unions.
Which Size Do You Need?
PlumBuddy valves come in three sizes. Choosing the right one depends on the diameter of your home’s main water supply line. Getting the size right matters — the valve needs to match your pipe for proper flow detection and reliable shutoff.
Available Valve Sizes
| Valve Size | Fits Pipe Size | Connection Size (NPS) | Common In |
|---|---|---|---|
| DN20 | 3/4” | 1” | Condos, townhomes, small single-family homes |
| DN25 | 1” | 1-1/4” | Most single-family homes |
| DN32 | 1-1/4” | 1-1/2” | Larger homes (3,000+ sq ft), multi-bathroom homes |
The DN25 (1”) valve is the most common size for residential installations. If you are unsure, start here — your plumber will confirm the correct size before installation.
How to Determine Your Pipe Size
You do not need to measure your pipe yourself. Your plumber will verify the correct size during installation. But if you want to check before ordering, here are several ways to find out.
Check Your Home Inspection Report
If you had a home inspection when you bought your house, the plumbing section usually lists the main water line diameter. Look for “main supply line” or “service entrance.”
Look at Your Water Meter
Your water meter or the line coming directly from it often indicates the pipe size. The meter itself may have the pipe diameter printed on it, or you can measure the pipe right after the meter.
Measure the Pipe
If you can access your main water supply line (usually in the basement, crawl space, or utility closet):
- Wrap a flexible measuring tape or piece of string around the outside of the pipe to measure the circumference.
- Divide the circumference by 3.14 to get the outside diameter.
- Use the table below to find your nominal pipe size.
| Outside Diameter | Nominal Pipe Size |
|---|---|
| About 1.05” | 3/4” pipe |
| About 1.315” | 1” pipe |
| About 1.66” | 1-1/4” pipe |
Note that nominal pipe size is not the same as outside diameter. A “1-inch pipe” does not actually measure 1 inch across the outside. The table above accounts for this.
Ask Your Plumber
A licensed plumber can identify your pipe size in seconds. If you are scheduling a PlumBuddy installation, your plumber will confirm the size as part of the pre-installation assessment.
Compatible Pipe Materials
PlumBuddy valves work with the most common residential pipe materials. Your plumber will select the appropriate fittings to connect the valve to your specific pipe type.
Copper
The most common pipe material in homes built after 1960. Your plumber can connect using threaded, union, or sweat (soldered) fittings. If soldering, the joints must cool completely before attaching the valve.
PEX (Cross-Linked Polyethylene)
Common in newer homes and remodels. Flexible plastic tubing that is easy to work with. Your plumber will use PEX-to-threaded adapters to connect to the valve.
CPVC (Chlorinated Polyvinyl Chloride)
Found in some homes built in the 1980s through 2000s. Your plumber will use compatible CPVC-to-threaded adapters.
Galvanized Steel
Found in older homes. Threaded fittings connect directly to galvanized pipe. If your home still has galvanized steel supply lines, you may want to discuss upgrading to copper or PEX during the installation.
Using Reducing Unions
If your pipe size falls between valve sizes, or if the exact valve size you need is not available, your plumber can use reducing unions to make the connection. This is a standard plumbing technique.
For example, if your home has a 3/4” main water line and you have a DN25 (1”) valve, the plumber can install reducing unions on each side of the valve to step down from 1” to 3/4”. This is a common installation and does not affect the valve’s performance.
Reducing unions are available at most plumbing supply houses. Your plumber will know exactly what parts are needed.
Connection Size vs. Valve Size
You may notice that the connection size (NPS) on PlumBuddy valves is larger than the valve size. For example, the DN25 valve (1” nominal) has 1-1/4” NPS connections. This is normal — the larger connection size accommodates the fittings needed to make a secure, leak-free connection.
Your plumber handles all of this during installation. You do not need to purchase fittings separately.
Still Not Sure?
If you are unsure which valve size to order:
- Ask your plumber. They can measure your pipe and recommend the right size before you order.
- Check your home inspection report for the main water line diameter.
- Contact PlumBuddy support at support@plumbuddy.co. Send us a photo of your main water line and we can help identify the size.
It is better to confirm the size before ordering than to receive the wrong valve and delay your installation.