Here is an easy one.
Every 6 months i go around the house and turn all the valves under the sinks and feeding the commodes back and forth about one turn.
This keeps them loose so that when you need to use one, you will be able to move it.
If they sit unused for years, they can be hard to turn when needed and might break when forced too hard.
Also leave them 1/2 turn away from fully open. This also makes it easier to break loose.
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