Plumbing Valve Basics

Comparing stop, gate and ball valves for use as water-supply shutoff valves.

By the experts at The Family Handyman

From The Family Handyman

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Step-by-Step Pictures and Instructions for Plumbing Valve Basics

Q: Our plumber, while doing some other work in the house, switched our main water supply valve from a gate valve to a ball valve. What’s the difference? Is one better than the other?

A: There are three basic valve styles, making this a classic case of good, better and best. All three can be used for water, oil or airflow control if the casting has “WOG" stamped on it. Stop valves are closed by screwing a rubber gasket down onto a seat in the middle of the valve. Pros only use small versions that act as shutoff valves for fixtures such as sinks and toilets and outdoor sillcocks. Flow is inefficient because of the circuitous route the fluid (water, in most cases) has to follow. It’s important to orient the valve in the right direction with the arrow (cast into the side of the valve) aligned with flow direction. That way, water flows against the bottom of the rubber gasket. If the valve is put in backward, the flow will force the gasket away from the top of the valve.