Water saddle valves are just plain wrong
In practically every home inspection the home inspector will see at least one if not more water saddle valves to be exact a self-piercing water saddle valve. These valves are universally part of ice maker and humidifier hookup kits. They are widely used because they are cheap and a fast simple install but are just plain wrong.
The saddle is placed around the water pipe with a rubber seal then tightened down against the pipe. When the self-piercing valve is tightened or screwed all the way in it pierces the pipe creating approximately a 1/4” hole. Then when backing off the valve water begins to flow.
Here is why
They are prone to leak over time, the rubber seal will eventually deteriorate and they clog up as calcium deposits build up at the small opening. Once they start to leak there is no easy fix. The right fix is to cut them out and replace them with a permanent valve. Often we will see three or four water saddle valves lined up in a row, with only the most recently installed one functioning.
If you are going to use one they should only be used on copper pipe and never on plastic of any kind unless it specifically specifies for PVC, CPVC or PEX piping. Keep in mind that most appliances now recommend the use of a full port valve and use of the saddle valve many void your appliance warranty. In some areas, they are a violation of plumbing code but as many other products which are sold in hardware stores.
Our recommendation, replace them with a permanent full port valve. These are available with compression, push on (also known as shark-bite) and sweat on valve connections and as always we recommend work by a qualified plumber.