Your shot was overexposed because even at f/22, 1/30 s still let in too much light for bright daylight. Also, 1/30 s is not really a long exposure for most effects.

To make daytime long exposures work:

• Set ISO to the lowest value available.
• Choose the shutter speed you want and check whether the camera can expose correctly at the smallest aperture.
• If it still overexposes, you need less light reaching the sensor.

The usual solution is a neutral density (ND) filter, which reduces light without changing color, letting you use much slower shutter speeds in daylight.

You can also use shutter priority mode to test whether your chosen shutter speed is realistic in the current light; the camera will indicate if correct exposure isn’t possible.

If you don’t have an ND filter, another option for some subjects is to take many shorter exposures and average/stack them later. This can mimic a longer exposure for things like water or other slow/random motion, but it won’t match a true continuous long exposure for fast-moving subjects.