Types of Gas and Water Supply Lines
Last updated September 7, 2023
Flexible supply lines bring water and gas from the permanently installed pipes behind your walls to your fixtures and appliances. Finding the perfect water supply line types, gas supply lines and connectors isn’t always easy if you’re new to this stuff though.
Our guide is here to help you learn the basics so you can get to work today.
Tip: Always turn off the gas or water before working on supply lines. Turn water back on slowly to check connection for leaks.
Table of Contents
Type of Supply Lines
Gas Supply Materials
Gas Supply Connectors
Water Supply Line Materials
Water Supply Connectors
Labeling of Supply Lines
Type of Supply Lines
Follow these steps to determine the supply line you need:
- Measure the distance between the appliance and the gas supply and add three inches to be sure it’s long enough.
- Refer to the manufacturer’s label on the appliance to identify the maximum gas input rating.
- Select a flexible supply line with a maximum flow rating capacity higher than the appliance’s input rating.
- Select the supply line with the connectors that match the appliance’s gas shut-off valve and inlet.
Gas Supply Materials
Gas supply lines are usually used for dryers, water heaters, gas ranges and fireplaces, and they are usually made out of copper or braided stainless steel covered with a sturdy plastic coating.
Gas Supply Connectors
Typically measured by outer diameter, which is designated as “OD” on packaging.
Common gas appliance connector types include:
- Dryer connector – 3/8-inch stubout MIP
- Water heater connector – 1/2-inch FIP inlet
- Gas range connector – 1/2-inch FIP inlet
- Gas fireplace connector – 3/8-inch stubout MIP or 3/8-inch flare fitting
Water Supply Line Materials
May be made of copper, but most are made of plastic, braided plastic or braided stainless steel. Research local regulations because some areas do not allow braided plastic supply lines.
Water Supply Connectors
To select the right connector, follow these steps:
- Determine the length you need by measuring from the inlet valve to the fixture, then add 4 inches to make sure it’s long enough.
- Select the connector size. Refer to the list below as a general guide for the most common connector types.
- Connector at Fixture: 3/8" male pipe
- Connector at Shut-Off Valve: 1/2" or 3/8" compression
- Connector at Fixture: 1/2" female pipe
- Connector at Shut-Off Valve: 1/2" or 3/8" female compression or sweat
- Connector at Fixture: 1/4" female compression
- Connector at Shut-Off Valve: 1/4" female compression
- Connector at Fixture: 7/8" ballcock
- Connector at Shut-Off Valve: 1/2" or 3/8" female compression or sweat
- Connector at Fixture: 3/4" hose thread
- Connector at Shut-Off Valve: 3/4" hose thread
Labeling of Supply Lines
Refer to the following designations on the packaging and labels to select the types of gas lines and water lines you need:
- NPT (National Pipe Tapered Threads): Industry standard for tapered threads used to join pipes and fittings.
- FPT or FIP (Female Pipe Thread): Female threaded fitting with the threads on the inside.
- MPT or MIP (Male Pipe Thread): Male threaded fitting with threading on the outside.
- Compression: Fitting that attaches to a standard compression thread on the valve.
Features of Supply Lines
- Water Hammer Arresters: Also known as mufflers. Stops the banging sound you hear when valves on washing machines, dishwashers and faucets slam shut. Also prevents damage to pipes and faucets.
- Corrosion Resistance: Built-in protection against corrosion.
- Deep Corrugation: Provides greater flexibility.
- No-Burst Hoses: Reinforced with stainless steel braiding.
- Right-Angle Connectors: Ideal for installing a supply line in tight areas without kinks or breaks.
Product Innovations
Certain connectors ensure proper pipe fit and operation and automatically shut off when a preset specified water flow amount has been exceeded. These help protect homes from water damage and are a smart buy whenever available.
Understanding the different types of water supply lines and gas lines can be tricky, but armed with a little knowledge for this guide, you can take on basic upgrades and fixes on your own. We have a range of products available to help you too, including many connector and riser types.
Need help identifying a tool or material? Find products fast with The Home Depot app. Snap a picture of an item you like and we'll show you similar products.
