Topic starter
We built our own house nearly 10 years ago doing most of the work ourselves.
Just got back from a 4 week holiday (when the heating has been turned right down) and found that we'd had a leak in the kitchen. The same happened last year.... when we blamed it on our flat roof and spent considerable time working out what we thought was a poor junction between flat roof and vertical wall and did some work with a roofer to improve it.
So clearly that didn't solve the issue. Cue worries that we've got a constant leak that we just don't notice in summer or in winter when the house is occupied and the heating is on. More digging and it turns out that *is* the case, but it's something far less worrying and stupid. It's the kitchen tap connection and so minor that have never noticed a calc build up, or drips on the pipe when in the cupboard under the sink.
So, the issue. All my plumbing is plastic/pushfit and it's been faultless. The only issues I had were where I had to resort to brass fittings.
It's a Blanco tap. The tails are 8mm to 3/8". Whereas UK connectors are always 1/2". You can buy replacement tails with push fit on one end, flexi pipe and the bit that goes into the bottom of the tap. But they're either 10mm or 12mm - NOT the 8mm that the Blanco needs (you really have to wonder why British plumbing still has all these incompatibilities with European).
Clearly I struggled with this 10 years back as I've got a compression fitting on the 15mm plastic which I really don't like the idea of. You can do it according ot the Hep2O manual, but should use a copper (rather than brass) olive. No idea what I actually did.
And it's clearly been leaking very slightly, for a long time. And it looks like I used some liquid PTFE to stop it leaking when I fitted it. Which didn't stop it leaking.
So, whats the best way to rework this? undo that compression nut and put a load of ptfe tape on it? or use some different fittings?
Hep20 make an adaptor for 1/2" tails (but not 3/8) and I found these adaptors but they're designed to go into a compression fitting not a push fit (not long enough from the looks of things)
Posted : 18/02/2025 1:57 pm
The fitting you have is fine, I'd just undo the nut on the compression side and remake with fresh jointing compound between the olive and fitting and tighten up again. If that doesn't work (unlikely);try with a new olive.
Posted : 18/02/2025 2:30 pm
I think this is what you're trying to describe? Seems to be the most suitable thing I can find to get you back to 1/2 inch fittings
Posted : 18/02/2025 2:31 pm
If it is the bottom/ blue pipe, and the leak is coming from the right hand nut, then just take it apart, clean it up, use pipe sealant, or liquid PTFE, and re-do it up. Or, better still, cut off a small section of the plastic pipe, re-do the connection with a new olive. I dont routinely use any sealant on compression fittings,and dont get any leaks. It’s possibly been tightened too much, so a new olive would be necessary, along with a small bit of the plastic cutting off. At most, 10 minutes and a new 15mm olive.
Posted : 18/02/2025 2:36 pm
Is this what you need?
https://tameson.co.uk/products/f29xy-press-fitting-15mm-male-r-3-8inch-male-copper-alloy
Posted : 18/02/2025 2:38 pm
Topic starter
I think this is what you're trying to describe? Seems to be the most suitable thing I can find to get you back to 1/2 inch fittings
That's exactly what I want - then I can have a Hep20 fitting on the end of the plastic pipe and it's all reversible. Again, seems ridiculous that those adaptors aren't available at either Screwfix or any of the mainstream plumbing places.
Posted : 18/02/2025 4:05 pm
Just remake the existing joint with a wipe of LSX sealant. Sort of cheating but usually works well.
https://www.screwfix.com/p/fernox-ls-x-leak-sealer-50ml/23614
Posted : 18/02/2025 11:33 pm
Might it be that you didn’t use a suitable insert in the plastic pipe? If it was the only compression fitting in the house I could see why you might not have had a box of metal inserts to hand
Posted : 19/02/2025 8:37 am
Do not use jointing compound on the plastic pipe. That is a simple connection you shouldn’t have any issues. If you use anything a couple of turns of PTFE over the front face of the olive.
Are you sure it is not leaking where the hose makes onto the brass adaptor, or even the hose itself?
Posted : 19/02/2025 8:46 am
I had no idea you could run plastic into a standard compression fitting. I've always put a short length of copper from the tap fitting into a pushfit isolating valve. Every day's a school day etc.
Posted : 19/02/2025 9:44 am
Ypu cant run plastic to standard compression fittings. They leak. You will never be able to get a seal as the plastic compresses. It just will not work. Nor should you put ptfe tape or goo in compression fittings.
Posted : 19/02/2025 9:51 am
Ypu cant run plastic to standard compression fittings. They leak.
Within the remit of a domestic water system, you can and done properly with BS EN 1254 compression fittings, they don't leak.
The only things that you can't do is get plastic anywhere near hot soldering, flux, etc. and join chrome/stainless pipes with plastic pipe push-fit joints
Posted : 19/02/2025 10:40 am
ThePinkster reacted
Why not go down simpler route and change the tap tails to one's that fit directly to the plastic pipe - https://www.toolstation.com/pushfit-tap-tails-300mm/p34559?store=GL&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&gad_source=1&gbraid=0AAAAAD-vLcVHRCRsawlwTbOWU8ZD0kXzQ&gclid=CjwKCAiAn9a9BhBtEiwAbKg6fpJ10qNmhbykapJgQIiMvCsonFQWGpqRTj4hEyqc3pNoOylk4IPyeRoCV9YQAvD_BwE
Posted : 19/02/2025 10:50 am
I always fit flexible tap tails with push fit connectors - life’s too short to be grappling with stuff under the kitchen sink.
Posted : 19/02/2025 11:02 am
TJ - you can use compression on plastic pipe. I’ve done it many times, the manufactures are happy with it too.
Make sure and use a liner, don’t use any jointing compound as some of them attack the plastic. You can use a little bit of PTFE on the olive but only a turn or two and it shouldn’t be needed.
I’ll qualify this by 30 plus years in the industry, probably nearer 40 when I think of working with my dad as a teenager.
First used plastic pipe (Acorn horrible stuff) in the mid to late 80’s.
Have moved on though to press systems for the last 15 or20 I would think.
Posted : 19/02/2025 1:26 pm
The only way compression fittings will leak on plastic pipe is if your doing it wrong.
It's a perfectly acceptable method of jointing.
For my Blanco tap tails..... I have all copper water feeds to sink. My plastic s only for the heating circuit.
I do recall having to get a special compression as you note but was a while ago now.
Posted : 19/02/2025 2:30 pm
Topic starter
Turns out it was the upper pipe leaking not the lower. So probably not tight enough, rather than the lower which I thought might have been over tightened.
italian adaptors overnight from amazon.
https://www.amazon.co.uk/GRIFEMA-G3-G1-Compression-Connector/dp/B087CG9JC2
pair of Hep2o push fit to 15mm
job done. Couldn’t replace the tails (as someone suggested) because they’re 8mm (not 10 or 12 as you can actually buy)
Posted : 19/02/2025 4:02 pm
Apologies. I missed out " without an insert"
Posted : 19/02/2025 8:00 pm