Surge damper stem tee adaptor leak

[Swilks93]

Hi. I set up my water on my Bailey unicorn Madrid this weekend and noticed a leak coming from the stem tee adaptor which is circled in red. When I had the pump on and taps open the water ran fine but as soon as I closed the taps it’s almost like the pressure built up and started leaking out this join. Is it likely to be a faulty tee or surge damper ? Has anyone else had this issue ?
TIA

 

[RogerL]

If the T-joint is leaking, it's faulty - drain the system down and re-seat each of the T-piece connections - if that doesn't work, replace the T-piece - remembering that both 12mm and 13mm are valid sizes so make sure you use the correct one.

 

[Hutch]

Did you drain the water system down over winter, if not there might be a crack in the T connector due to freezing.
But Rogers tip is well worth checking, look for cracks when you have the T out.