how do i stop my overflow pipe dripping?

Additional to other answer
If adjusting the float does not work then a new washer [there are various types according to the valve type] inside the valve attached to the float arm where it enters the cistern
A float on a metal arm can be adjusted by bending the arm downwards

crumple
October 2009

the water tank in your loft, the ballcock in it is not knocking the water off all the way , so its ove flowing out the over flow pipe at the side of your house. you or somebody needs to go and ajust it , or or bend the arm of the ballcock down just a little, to cut the water off , before it get to the over flow, but be care full when bending it , that it dont snap off , or you can get a new ballcock, and just replace it .

mark
October 2009

The drip will come from a toilet cistern (easy to check by taking the lid off) or from a tank in the loft (more difficult to check).

The cause will very probably be an inlet valve that needs adjusting - sometimes the rubber of the valve has perished and will need to be replaced - there is another more sinister reason but it's very, very rare.

To adjust the inlet valve operation either lower the float further into the water (to shut the valve off sooner) or if it has a nylon adjusting screw, just screw the adjuster in towards the valve and tighten any locking nut.

Good luck...

Peccavi
October 2009