How to connect to 3/8 hose?


19 Jun 2016
Reaction score
United Kingdom
This is my first attempt at changing a tap :) But I am stuck as to how to connect the hose to my existing pipework. Can you please tell me what part I need

I am trying to fit a new Grohe kitchen tap. The hose appears to be 3/8". The isolation valve is on a 15mm pipe. I hope the photos help.

How do I connect the 3/8 hose to the existing 15mm isolation valve?

It looks like I will still need another metal hose as the Grohe hose is not far enough?

And is this only an issue because I bought the tap from a German eBay seller?

Thank you.

Last edited:
Sponsored Links
Thank you @muggles . Screwfix isn't far so I'll give that a go. But it seems to me as if only one end of that connector is threaded and the hose and isolating valve in my situation are both threaded.

You'll need a nut and olive on top of the existing isolating valves.
  • Thanks
Reactions: r_c
Sponsored Links
You are missing the nuts and olives from the top of your ISO valves. I presume the previous installer just nipped the flexi's straight onto the top of the ISO.

You need 2x15mm nuts and 2 olives.
  • Thanks
Reactions: r_c
The finished product. New tap seems to be working well. Thank you all for your help with this! :)

I now want to go and learn how olives work!
At the end of installing this tap I had a small white sachet from Grohe with German writing on it. Google Translate tells me the German says "synthetic grease".

Have a missed a step?
Not really, you use the grease to lubricate the o-rings that are on the tap end of the flexi tails, just ensures they slot into the hole properly. As long as it's not leaking then I wouldn't worry.
  • Thanks
Reactions: r_c
I have a random IV in my plumbing box with an unusual fitting on one side, maybe it is for these new fangled microbore tap cons

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links