As per title really – water ballcock not closing valve in cold water tank – am I right in thinking that I can bend the arm down/up? of the ballcock as a temporary measure?

Water is currently pi55ing out the overflow at a rate of knots!!

Bend the arm down, but ultimately you probably need a new valve

if you raise the ball manually does the inlet valve stay open or does it close (i.e. can you shut off the intake by lifting the arm?)

if yes, then yes, you can possibly solve it by bending the arm, but if the valve seat is mucky and you need to lift the arm with some force to close it, then you might nor be able to rely on the flotation of the ball to shut it off when you’re not there

Check that the valve will actually close and stop the water flow if you lift it up, if not, the valve is fekked… but yes, gentle bending of the arm downwards should do it…. try to not stress the valve in the tank… I was clumsy and broke the pin holding the ballcock arm… nice and easy does it.

Im not a plumber, but IME it doesnt normally come out that fast, so before touching anything Id make sure I knew where to turn the water off.
Then id gently lift the arm to see if that stopped the flow, if it did id look for a threaded adjuster on the valve/arm. If that didnt work I might bend the arm down.

Some cisterns have a little adjuster screw to preload the valve as it were. This can save you snapping the thin copper tube arm if you’re a bit ham fisted with it, causing plenty of faffing untill the plumbers’ merchants opens tomorrow.

I’d try replacing the washer first before any major plumbing works.

When I lift the arm – it pushes a black pin in to close the valve, however, when I let go of the arm,the pin comes back out slightly letting the water continue flowing.

I have tried bending the arm down, but I don’t want force it too much in case I break something.

In that case if you’re nervous of snapping something tie the arm up to a piece of wood (e.g. a broom handle) propped over the tank until you can get to the plumber merchant / get a plumber in. Untie it when you are about to use a lot of hot water.

please see photo below – I’ve put a red square around what looks to be some kind of ‘in-line’ valve (sorry I don’t know the correct term) which seems to be on the pip letting the water in?

If I close that will I close problems elsewhere? Just for overonight till I can get a plumber out?

yep, you can stick your screwdriver in there and shut off the line in, but as The Brick says, dont run your hot water (much) with it closed as you’ve shut off the supply.

yeh turn the valve off with a screw driver, just a quarter turn will do it.. tomorrow pop down b and q get a valve and a new ball and fit em yourself with an adjustable spanner.. easy.. total cost less than a fiver!

Thanks chaps, have shut off the line in by using a screwdriver.

Don’t know whether I trust myself to attempt it on my own! – Its looks pretty easy, but it looks very easy to have water everywhere!

its a piece of piss. Having shut off the supply side, you can safely replace the ball float valve.

something like this?

http://www.diy.com/nav/fix/plumbing/plumbing-supplies/toilet_fittings/-specificproducttype-valves/Ball-Valve-High-Pressure-16131201-1-2inch-Part-2-9270919

EDIT: how do I know if I need high pressure or low pressure?

that ll do you.. get a new ball as well.
get rid of about half the water in the cistern by opening a hot tap..
with the isolation valve still closed. undo the brass nut that secures the pipe to the valve. ( a little very little water may escape) be cautious you need to keep the little fibre washer thats in the end of the brass nut intact.
remove the plastic nut on the outside of the tank. remove the valve and ball. fit new ball to new valve tighten it nicely but dont overtighten.
take one of the white plastic nuts off the new vale and adjust the second so that it is approx. the same distance in as on the original valve..
thread the valve through the hole in the cistern put the second plastic nut on to the outside of the tank so that the new valve is secure..
re attach the brass nut ( and red fibre washer ) all secure?
open the isolation valve a qtr turn, if the brass nut leaks ( thats the only place it can/ will give it a little tweak ( your fastening a little nut not securing the forth road bridge!)
check agian for leaks and that the ball valve closes whan the cistern is full..all okay?
go downstairs and boast of your handymaness to any passing honeys..

I read that as ‘bollock’

your other problem is that 22mm vent pipe terminating below the top of the tank 😯 , you need to cut it so it is level with the top of the tank so it cannot go below the water level if it as now overflows.

Take out the old one and take it to b&q when you go to get the new kne. The nice old men there will make sure you get the right bits and show you what to do. That’s service.

Excellent it’s not just me that has Sunday night (all the shops are now closed) plumbing issues! Managed to screw through a heating pipe in two places teatime yesterday water ished through the ceiling about an hour later. Had to drain the heating, scrabble round in the loft, rip up floorboards, managed to stop the leak in the 2 1/2 hours it took British Gas EMERGENCY service engineer to call back, fail. Will now be waiting all day no doubt for plumber to turn up. Schoolboy error 😳 BTW easy to fit a new ballcock as has been said!

thanks for input chaps, will be attempting it later!

Anybody know if I need high pressure or low pressure type?

Not sure I want to remove the existing one without buying the new one first..

high pressure as its mains water, while you are at it i would drain it down and give the tank a good clean out looks a little dirty in there

Just a quick note to say thank you to the people who offered advice – I have successfully replaced the valve.

STW is ace!