When i first came here i was amazed to see how much teflon tape local plumbers would apply to threaded connections but after trying i bit of DIY plumbing i know why. I only had a few ball valves and T pieces to join together, i used the teflon tape but probably not as many wraps as i had seen local guys using and the result at switch on was total disaster, every joint leaked even though they were very tight. I think so much tape is required because all the fittings seem to come from China and the threads are not what they should be. I remember when i was an apprentice (just) we used to use stuff called stags paste for any dodgy threads, it was red stuff that went rock hard and never leaked, the only problem was if you needed to take it apart again. That will be my next quest at the hardware shops.
Best of luck on your hunting. The game here tends to be elusive, and makes for a celebration when found.
Teflon tape used here by Workers is 1cm thick. Best in all cases to use 2cm thick. It is not found in all Hardware stores but is in most. I have always used 2cm and also make sure threads are dry on both contacts. Always apply more as it can be peeled back if applied too thick. Better more than not enough which of coarse is the main cause of leaks over time.
And if that fails you can always add another 4cm of that thick elastic black rubber tape to the outside of the joint/leak.
To be more specific for those who have leaking pressure pipes. You cannot seal a leak in a pressurized pipe from the outside. The water pressure will just work its way past the adhesive. Wrapping the outside with tape may work for sewage or other uses that are not under pressure.
But IF you use teflon tape on the threads surely the water pressure of any leak will be low and an external binding might help - even if to the point at seeing a dribble of water rather than a larger amount and realising a repair needs to be done.
