To adjust the water level in a toilet tank if you have a Fluidmaster fill valve, turn the adjustment screw that is connected to the float clockwise to raise the water level. Turn the adjustment screw counterclockwise to lower the water level in the tank. Check out more home improvement tips in our e-books https://www.amazon.com/gp/product/B0B2KW1FQ9?notRedirectToSDP=1&.