pH probe

so i bought a pH probe tool from Lowe's. It seems to work good in the soil but when I test my h20 before i water the plants it doesnt seem accurate. if i hold the probe towards the top of the container with h20 the pH reading is 7 but when i put the probe deeper in the watering can it goes really acidic like 4 or 5.

any ideas why?

The probe is just for soil.