Deplumbing a dishwasher - versus flooding the place. Help!

[iloverhubarb]

We thought we could do this ourselves - just take out an old dishwasher and replace with new. Pulled old dishwasher out, unplugged, and turned off what we thought was input tap (just for dishwasher, not stop cock), so it was across the pipe at 90 degrees (this was as far as it would go). Started to unscrew the dishwasher input pipe. Water drips, then gushes. Screwed back on hastily, got towels, kept calm.

Found stop cock, a proper old fashioned tap. Turned clockwise till fully off. Ran taps in kitchen sink, no water now coming into kitchen sink. Think we're ready to proceed.

At this point we became aware of gallons of water pouring out of the overflow pipe outside from the toilet UPSTAIRS! Turn stop cock back on (as turning it off seemed to have caused this - huh?) Water slows down and stops. Not quite sure of the sequence here. Can anyone explain what on earth was going on? And surely I don't need to empty all water in the house before removing a dishwasher?

We have direct water by the way - no tank in loft. Will be calling a plumber to help on Monday as it gave us the willies. Thank god for overflow pipes. Just abit chastened/intrigued.

I might be able to help with your initial problem, of water running despite input tap being off... we had the same thing. It turned out that the plastic part of the tap was broken, so turning the tap did not actually close the valve. We closed the valve with an adjustable spanner and it was all fine. You can buy new valves with taps quite easily, though I couldn't find a tap by itself.

sorry, can't help with the toilet. that's weird.

upstairs WC cistern overflowing - my guess is that fiddling with the stopcock dislodged limescale, rust or dirt into the pipe. Modern silent cistern filling valves have a tiny waterway to operate the silent close, and are very prone to grit particle problems. Probably you have an Armitage Shanks or older Torbeck valve (there will be a very small float, not a big plastic ball).

If you turn off the stopcock and unscrew the cistern valve, you will probably find it has grit in it. Wash it out well and reassemble with great care (it may have a needle that fits into a tiny hole in the diaphagm)

The new Torbeck is bigger, but is reputed to be even better than the Fluidmaster, and is also very quiet, so if you decide to get a plumber in, ask what it would cost to change.

If the cistern is a modern one with two press buttons on the lid, it might be trickier.

Thanks both bonzo and Piglet, both points make sense. Would never have worked out possible WC cistern link. You're right Piglet, the valve is a flat rubber diaphragm type thing, not a ball, attached to a chain. Looks pretty old fashioned, though the valve itself has been replaced (by same type) in last year as old one started to leak.

After yesterday's shock I do not plan to try to look at the valve myself in case something really disastrous happens. Plumber booked in. But I will watch him carefully, and also discuss whether good to change cistern valve. Very much appreciate your comments. Thnaks

t5he "flat rubber diaphagm" will probably be a Flapper Valve. They give a powerful and quiet flush. The rubber seal can perish with ages, especially (I am told) from cidtern blocks.

It is actually quite a new invention! and very siimple. If you are handy you can buy a spare flapper and fit it yourself next time, it is much easier than changing an old syphon, as you do not have to turn off the water and remove the cistern.

If you have a flapper and no round float, you probably have a Fluidmaster filling valve

flapper

fluidmaster

I was thinking you had one of these tiny things, which are quite prone to grit problems, but extremely silent