Toilet Water

Maybe by adjusting float level up or down. Or maybe your vent stack is plugged and too much water is getting siphoned out of it. Or maybe it is designed to have that amount of water in it based on its trap, or something is leaking down across its trap (crack?).

Has it recently changed from what it used to be?

The actual level is fixed by the design of the trap inside the bowl. But the "refill" tube in the tank must supply enough water down the tank overflow pipe to completely fill the bowl after a flush. Watch what the refill tube does while the tank is refilling. Should be a steady stream into the overflow until the tank is finished filling.

Note that many newer toilet bowls have a smaller "water spot" than older ones. You can test to see what the design level is: Very slowly, pour a bucket of water into the bowl. The resulting water level is the design maximum.

Jim

Exactly, and you can look for a new model with a larger "water spot."

Such as American Standard Cadet.