Water keeps filling from output valve

[userrrr]

Water keeps filling up my home water tank from the output valve at the bottom of the tank and not from the top of the tank

Water keeps pouring in from the output valve and won't stop, making the tank overflow 24/24

At first we thought it was the input valve at the top but after inspection we found that water kept filling the tank even if the input valve was shut
Please help

 

[ShaunCorbs]

How is the tank fed ? As the both pipes connected so can’t be rain water so must be a store for a pump

Nrv probably failed to the left of the tee / rubbish in it