Basic plumbing help/advice re leak!

[north2south]

Hi all

I had a dishwasher installed yesterday and now the flat below have had some water leaking through their ceiling.

I think the issue is a dripping something under the sink - or residual water from the installation.

Is anyone able to tell me what this thing with the blue circles on is? And ideally how to fix the dripping?!

https://ibb.co/6DCx475

Thanks so much

[bigmacca1]

That round thing with the blue stripe on it looks like an isolation valve ? You would be best to ask whoever installed it for you to come and check the pipework and dishwasher drain pipe,

Hope this helps.