Q Hi, Ed. Call me old-fashioned, but I still wash my dishes by hand, and I'm tired of wasting the water by keeping the flow running all the time! Once I find the right temperature, I can't keep turning the faucet on and off or I lose my setting. Can a valve be installed on my spout to stop the flow and keep my settings? Why has no one thought of this?
— Jim, Arizona
A Jim, you bring up a good question, and I'm sure many people have wondered why faucet spouts have no shut-off valves. Believe it or not, there is a very good reason to keep a faucet flowing constantly. The reason is that a plumbing problem known as crossover can occur if faucet flow is stopped at the spout.
I love to explain crossover to people because it's such an interesting phenomenon. Believe it or not, hot- and cold-water lines are two completely different systems in your home. A cold-water line will feed your water heater, but the hot-water lines leaving the water heater are now a separate system and should never make a direct connection to the cold lines. Hot and cold lines meet again only at places such as faucets, where a mix will take place and create usable temperatures as long as a constant flow through the spout is maintained. But if that flow through the spout were completely stopped while the faucet hot and cold handles remained open, you'd have just made a direct cross connection between the hot- and cold-water lines in your plumbing system. That is a big no-no. And it is here where things get really interesting.
People are also reading…
Whenever hot- and cold-water lines make a direct connection, the hot water will travel into the cold-water lines throughout the house — and I mean travel! You can actually get hot water coming out of your cold-water fixtures, creating an unsafe condition. That's why showers and sinks do not use complete shut-off valves on the spouts.
You can, however, buy restricting aerators for your faucet to slow down the flow, and some even have levers for a strong flow and a slow flow setting. That's one option. You also can get special cooking faucets with a spray head that will stop the flow temporarily while you squeeze the lever, but as soon as you let go, the water flow is returned.
As far as completely stopping the water from passing through a faucet spout, most plumbing codes will not allow it. So I'm afraid you'll just have to . . . go with the flow!