Leaking Hot Feed to cloakroom hot tap.

The brass fitting is a 3/8” MI to 15mm compression .

Between the flexi and the brass there will be a rubber washer, it may be captive in the flexi. First thing to try is to just nip it up a bit.

Although looking at the photo again it looks as if the water is actually coming from the compression end of the fitting and running down to your red mark. With two spanners try tightening the compression end.

Thanks for the response.

The nut size on the brass section appears to be around 24 - 25mm. The Flexi nut according to the Hansgrohe instructions is 19mm which seems about right (although as mentioned above it appears it might not actually be the OEM flexible pipe from the tap that has been used). It's difficult to measure both accurately with what I have.

I did wonder if the brass section was leaking myself but it does appear if I use a small piece of toilet roll paper to check the water appears to be between the bright silver coloured fitting and the brass fittings and not in-between the brass nuts which is where the drip does appear to form.

I did try nipping it with adjustable spanners but it hard to feel it so will try and source the correct sizes to do it properly.

Thanks again.

Actually you might be right. I might try and find a plumber to have a look as I really don't want to cause more damage lol. If I can find a plumber for such a small job. 😬

It’s probably a 1 minute job, only problem is if it goes wrong you need the experience and potentially parts to put it right.
If you can speak to a local plumber it’s a £20 on your way home job 😊