Plumbing Fittings Question:

If your water pressure is so high that it leaks past a Fluidmaster 400A or another new ballcock (aka: "toilet fill valve") - then you NEED a pressure reducing valve. Other water pipes, connectors, clothes washing machine hoses and your water heater could leak or break. Best to get a pressure regulator if your pressure to the house is more than 60 pounds (80 is code throughout most of the U.S.).