Leaky water connections


I’m having problems with the connection between the first NPT to barb adaptor and the solenoid valve inlet. It leaks! The NPT screws on ok and I twist until it won’t go further. (I’m pretty sure I haven’t confused it with the hose adaptor). I’ve tried wrapping the whole of the tape roll round it, but still it leaks.

See the video:


Has anyone else had this? I wonder is the plastic thread might be defective, although it looks good to me. Wrapping in tape seems like a bit of a botch job anyway: I would have thought it’s essential to get a watertight screw connection first.



Hi @SimonB,

The teflon tape goes inside (on the threads) and needs to be applied clockwise. The following video might help:

Good luck!


Brilliant! Thank you!

@SimonB I had a similar issue and I opened it up to find no O-ring. The brass fitting is designed to seal using a square-profile O-ring as it is not tapered thread. The tape is likely to leak eventually but an O-ring will last without having to over crank and destroy the threads.


When you say you opened ‘it’ up, does ‘it’ mean the solenoid? I’m not clear what an o ring is or how to recognise it.



Sorry, yes, I see it. Inside the black pressure valve. Thanks for the suggestion.

Now it works perfectly! The plumbers tape, correctly applied, made all the difference.

May I suggest augmenting the instructions here:

To include details of using the tape?