Water tank overflow pipe dripping

First of all hi to all here as this is my first post for help as a new user of this grate site.

My problem as stated above is the overflow pipe on my cold water tank that is located in the loft. The problem started around 2 months ago. Some times the dripping can be very fast, more of a flow that a dripping really.

I have adjusted the ball end, and that sim to work ok as it does stop the flow of the water. The only thing that I’m not quite sure if it's right or not is the overflow pipe inside the tank. It’s the elbow type. The water flow stops way bellow the horizontal point of the pipe. The vertical point it’s not quite vertical, it’s in an angle and half of it it's in the water. My question is, does the overflow pipe need to be in the water.

Many Thanks for any advice
Nikos

The level of the water just needs to fall below the over flow pipe, if its coming into the tank then has an elbow dropping it down a few inches use the end of this as a guide and set it to fill till it just covers the end of the overflow pipe. It doesn't need to be under water, you just want as much volume of water in there as possible with out it overflowing.

Gobz

Thanks a lot Gobz.
In order to get as much water in the tank as possible I will have to adjust the overflow pipe on the inside to come out of the water. Is that correct?

You don't need to change the overflow outlet, just adjust the level it fills to by adjusting the ball cock a little. If it fills to a reasonable level (i.e 3/4 full) since you adjusted it it will probably fine as it is.

Gobz

if you run a tap, to draw some water off and drop the water level in the tank, and you hold the float ball up (lightly) with your hand, does water still come out of the valve?

If no, have you got a mixer tap such as a shower, especially a ceramic one with a joystick rather than two knobs? this being a mixer tap where the cold is at Mains pressure and the hot is from the tank? Most often happens at sinks? Possibly a mixer that has been fitted about as long as you have had this problem, or maybe an older one that has got worn out?