Plumbing Supply Lines, Hoses and Shutoff Valves

Plumbing supply lines, hoses and shutoff valves connect your faucet or appliance to the water supply and let you shut off water where you need to work. A flexible connector handles a tight or offset connection, and a fixture stop lets you shut down one sink without cutting water to the whole house. Buy them as a matching pair: the pipe connection, valve outlet, fixture connection and hose length all matter.

Shutoff valves: choose the connection and the turn

Buy a quarter-turn stop for a fixture replacement. It opens or closes with a 90-degree turn, giving you quick control without winding a multi-turn handle through several rotations. During Montana’s winter interior renovation season, that individual shutoff is worth having: you can work on a bathroom faucet while the rest of the house still has water.

An angle stop turns the connection 90 degrees toward the fixture. Choose it where the pipe comes out of the wall. A straight stop keeps its inlet and outlet aligned and suits a pipe coming through the floor.

The angle-stop choices include 1/2-inch pipe thread by 3/8-inch compression and 5/8-inch compression by 3/8-inch compression. The 3/8-inch outlet is the usual starting point for a faucet supply connection. Match the other end to the pipe coming into the valve.

Here is the sizing detail that saves confusion: 1/2-inch nominal copper tubing measures 5/8 inch outside. A 5/8-inch compression connection and a 1/2-inch pipe-thread connection still use different joining methods. Buy by connection type as well as the number.

For a different outlet, the angle-stop choices also include 5/8-inch compression by 1/2-inch compression, 1/2-inch pipe thread by 1/2-inch pipe thread, and 5/8-inch compression by 1/2-inch pipe thread. Choose those to match the attached connector. A larger number alone is no reason to change sizes.

For PEX shutoff valves, match the connection system. PEX crimp and PEX expansion stops are distinct choices, and a compression connection on PEX needs a PEX-rated stop and the correct insert. Start with the pipe and connection already in the house.

For a washing machine, the 1/2-inch pipe-thread by 3/4-inch male hose-thread valve belongs with the washer connection. Keep its handle accessible. A shutoff you can reach is more useful than one buried behind the appliance.

Faucet supply lines: match both ends, then choose length

What size are faucet supply lines? A common shutoff outlet is 3/8-inch outside-diameter compression, but the faucet end must match the faucet. The same rule answers what size supply lines you need for a bathroom faucet or kitchen faucet: check both connections. The room does not determine the fitting.

The stainless-steel faucet supply choices here have a 3/8-inch compression connection at one end and a 1/2-inch female pipe-thread connection at the other. For sink faucet supply lines with those two connections, this is the combination to buy.

Faucet connector	End connections	Lengths
Stainless-steel faucet supply line	3/8-inch compression by 1/2-inch female pipe thread	9, 12, 16 and 20 inches
Stainless-steel faucet supply line	3/8-inch compression by 1/2-inch female pipe thread	24, 30, 36 and 48 inches

Measure the distance between the shutoff and faucet connection before choosing length. Buy enough hose to make a relaxed connection without pulling on the nuts or crowding the cabinet with excess slack. A short hose keeps tension on the connections; too much hose can kink. Flexible supply lines are the right choice for tight or misaligned spaces because they accommodate the offset.

For IPS faucet supply lines, the thread type is decisive. IPS means Iron Pipe Size, and IPS threads do not interchange with compression fittings of the same nominal size. A 3/8-inch pipe designation is different from 3/8-inch outside-diameter compression. Matching numbers are only half the match.

For extending faucet supply lines, buy a single longer connector with the correct ends. The 30-, 36- and 48-inch lengths give you longer choices without joining two faucet supply lines together. That is the clean choice when reach is the problem.

When replacing bathroom faucet supply lines, shut off the water before disconnecting them. Hold the valve body with a backup wrench when tightening its outlet nut so you do not twist the pipe stub. Compression threads are not the sealing surface, so leave thread tape off compression connections. More wrench force is not a better seal: overtightening can deform the ferrule and cause a leak.

Ice maker supply lines and kits

For a refrigerator connection with 1/4-inch compression fittings at both ends, buy the matching ice maker connector. The stainless-steel choices include a 24-inch line and a 10-foot line. Choose the length for the distance and the space behind the refrigerator, leaving the connector free of sharp bends when the appliance moves back into place.

There are also 72-inch ice maker connectors, 6-foot poly connectors and a 25-foot poly installation kit. Choose the kit for a job requiring that longer tubing run; choose a finished connector for a matching connection between the shutoff and refrigerator. Keep length and end fittings together in the decision. Extra tubing does not solve a mismatched connection.

Toilet supply lines

Most toilet fill valves use a 7/8-inch ballcock connection at the tank, and a typical toilet hose uses 3/8-inch compression at the stop. Match the actual shutoff connection before choosing the hose. Pipe thread and compression remain different here, too.

The toilet connector choices include 12-, 16- and 20-inch lengths with a 7/8-inch ballcock tank connection, plus a 16-inch connector with a 1/2-inch female pipe-thread valve connection. Buy the length that reaches the tank without pulling tight or folding behind the bowl. The tank fitting and the valve fitting each have a job to match.

Dishwasher supply lines and fittings

Choose the dishwasher supply by its inlet connection and the clearance beneath the appliance. The choices include a 1/2-inch female pipe-thread supply, a 3/8-inch compression connector and a separate dishwasher elbow. Match the elbow to the appliance connection before buying it with the hose.

Flexible braided hoses suit dishwasher connections, and elbow versions help make the turn where space is tight. That turn deserves attention: awkward bending can damage the stainless-steel weave or crush the internal hose and reduce water flow.

Metal ball valves

Buy a ball valve where you need on-and-off water control in the pipe run. Its lever gives you quick shutoff. For one faucet or toilet, choose the fixture stop that also puts the hose connection in the right direction.

The full-port metal ball-valve choices include 1/4-, 3/8-, 1/2- and 3/4-inch female pipe-thread connections, along with a 3/4-inch sweat version. Match the valve to the pipe size and joining method. The sweat connection belongs with a soldered copper connection; the female pipe-thread version belongs with a matching male threaded connection.

SharkBite brass ball valves include 1/2- and 3/4-inch sizes, plus a 1/2-inch version with a drain. Choose the size and connection for the pipe you are shutting off, and the drain version where your job calls for that feature.

Washing machine supply hoses

Washing machine supply hoses use standard 3/4-inch garden hose thread. Buy washer hoses for those connections, keeping them separate from the machine’s wastewater discharge hose.

The length choices include 4, 5 and 6 feet. A 72-inch stainless-steel pair gives you two hoses for the hot and cold connections. A 6-foot hose with a 90-degree end is the pick when the connection needs to turn close to the wall. Buy for the space behind the machine as well as the distance to the valves.

If the pipes bang when the washer operates, ask about a water hammer arrestor with the connection parts. It absorbs the shock that causes the banging. Adding hose length is not the fix for that problem.

Appliance supply connectors

For an appliance with 3/8-inch compression connections at both ends, choose the matching stainless-steel appliance supply connector. Lengths include 12, 16, 20, 36, 60 and 96 inches. A separate 72-inch choice has 3/8-inch compression at one end and 3/8-inch male pipe thread at the other. Those ends make it a different purchase, not just another length.

Buy the connector for the appliance connection and available space. Keep water supply and drain or discharge connections separate. If the project also needs an outlet box, choose it around the appliance, shutoff access and available space; a washing machine box brings together hot water, cold water and the drain connection.

The Pick

For a wall-fed faucet, buy a quarter-turn angle stop that matches the incoming pipe and your supply-line outlet. For a faucet with 3/8-inch compression at the stop and 1/2-inch female pipe thread at the faucet, buy the stainless-steel faucet connector in the length that reaches without tension or a kink.

For a refrigerator, buy the 1/4-inch compression ice maker line when both connections match. For a toilet, buy the 7/8-inch ballcock connector with the correct valve end. For a dishwasher or washer, buy the dedicated appliance hose, choosing an elbow end where clearance calls for the turn. For shutoff in the pipe run, buy the matching metal ball valve.

Frequently Asked Questions

What size are faucet supply lines?

A common shutoff connection is 3/8-inch outside-diameter compression, but the faucet end varies. That applies to both kitchen and bathroom faucet supply lines, so match each end separately. A nut marked 3/8 COMP identifies a compression connection; a 3/8-inch pipe-thread fitting isn’t interchangeable just because the number matches.

Can I connect two faucet supply lines to make them longer?

A single longer faucet supply line with matching ends is the better choice when you need more reach because it avoids an extra joint. Measure the distance between the shutoff and faucet connection, then choose enough length to connect without pulling on the nuts. Extra length needs room for a gentle bend; excess slack stuffed into the cabinet can kink.

How do I connect faucet supply lines?

Whether you’re installing a new faucet or replacing bathroom faucet supply lines, shut off the main water supply and open a nearby faucet to relieve pressure before disconnecting anything. Use a backup wrench on the valve body while tightening the outlet nut. Follow the connector’s tightening instructions rather than giving every fitting an extra turn: overtightening a compression nut can deform the ferrule and cause a leak. After restoring water, wipe the joints with a dry tissue to spot small amounts of seepage.

What type of water shutoff valve should I use?

For a fixture, choose an angle stop when the pipe comes out of the wall and a straight stop when it comes through the floor. A quarter-turn version gives you full open-and-closed control with a 90-degree handle turn; a multi-turn version takes several rotations. For on-and-off control within a water pipe run, choose a ball valve with connections and published pressure and temperature ratings that match the job.

What shutoff valve should I use with PEX?

Choose a PEX shutoff valve that matches your connection system. Crimp versions use a crimping connection, while expansion versions require an expander tool to widen the tubing before the fitting goes in. If you’re using a compression stop, choose a PEX-rated version and use the correct insert. Match the outlet separately to the fixture connector, since the PEX connection only settles the pipe side.