Shutoff valves

Entry in Fittings and valves · Updated October 29, 2026 · Written by the Know Your Pipes editors from the sources listed under References

A shutoff valve stops water in a supply pipe; in the ball valve vs gate valve comparison, a ball valve turns a drilled ball crosswise with a lever, while a gate valve lowers a gate with a handwheel. Homes also use small fixture stops under sinks and toilets.

Every house with piped water has at least one main shutoff where the water service enters, and usually more valves on branches, at the water heater and at each fixture. Knowing where the main valve is, and that it turns, is the first step in handling a leak or a burst pipe.

1 Ball valves

A ball valve has a ball with a hole through it, held between two seats. Turning the handle lines the hole up with the pipe to open it, or turns it sideways to close it. Makers sell ball valves in full-port form, where the hole is close to the pipe's bore, and reduced or standard-port form, where it is smaller^[2]. One maker's catalog marks both its full-port and reduced-port ball valves "not recommended" as throttling valves, meaning they are built to sit fully open or fully closed^[2].

Ball valves come with threaded, solder, plastic or flanged ends, and some are made with PEX connections built in, such as ASTM F1960 expansion ends, so the valve joins the tubing without a separate transition fitting^[5]. The handle position shows at a glance whether the valve is open: in line with the pipe is open, across it is closed.

2 Gate valves

A gate valve has a wedge-shaped gate that a threaded stem raises out of the waterway or lowers across it, so the handwheel takes several turns to open or close. Bronze gate valves are sold in rising-stem and non-rising-stem forms for hot and cold water and general utility service^[3]. On a rising-stem valve the stem climbs as the valve opens, which shows its position.

3 Fixture stops and manifold valves

Under a sink or toilet, a small stop valve on the supply stub lets one fixture be isolated. With PEX supply, the tubing can run to the stop, transition to a copper stub-out that takes a solder, push-fit or compression stop, or connect to a push-fit valve made to ASSE 1061^[5]. More on those joints is in compression fittings and push-fit fittings.

In a manifold (home-run) PEX system, each line can have its own valve at the manifold. The 2024 International Residential Code, Section P2903.9.4, says fixture valves, where installed, go at the fixture or the manifold, and manifold valves must be labeled with the fixture they serve^[4]. A plumbing industry guide adds that manifolds with valves must be accessible and protected from freezing^[5].

4 Lead-free rule and certification

Valves that carry drinking water are covered by the Safe Drinking Water Act's lead-free definition: no more than a 0.25% weighted average of lead across wetted surfaces^[1]. Some products are exempt, including water-main gate valves 2 inches in diameter or larger^[1]. Certification to that limit is shown by marks for NSF/ANSI/CAN 372 or NSF/ANSI/CAN 61, and brass parts are the usual concern.

Supply houses stock valves by type, size and end connection; PlumbingSupplyAndMore's ball valve category (PlumbingSupplyAndMore has the same owners as this reference) is one example. Replacing a main shutoff means shutting off water at the curb or meter and often needs a permit, so it is work for a licensed plumber.