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Discuss Bristan shower mixer leak in the Valves & Taps area at

  1. Carl1

    Carl1 New Member


    My Bristan shower mixer (pictured) has a leak from the shower head. The amount of water seems rather pressure dependent, varying if you turn the shower on and off again, and if the tap or loo is used. A plumber replaced the cartridge some months ago, but the problem seems to have continued intermittently since then. What is it likely to be?


  2. Phil

    Phil Plumber

    Get him back, just because the cartridge has been replaced some showers can still drip as other O rings (depending on make) need replacing also.
    Like the Aqualisa ones, if you dont replace that O ring right at the back which is tricky to get out it can lead to a dripping showerhead even with a new cartridge.
  3. Shower Engineer

    Shower Engineer Plumber

  4. Carl1

    Carl1 New Member

    Thanks, Shower Engineer. Is the link you sent just to give an idea of what to search for, or are you confident that it will fit my exact model? I removed the controls (see image) if it helps. 20170520_172053.jpg
  5. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    looks like a bristan quest exposed
  6. Shower Engineer

    Shower Engineer Plumber

    Yes they are the correct parts.

    1. Remove the brass nut and large plastic ring that operates the piston assemblies.

    2. Remove the blue and red discs by levering with a small screw driver.

    3. Undo the piston assemblies, this is the hard part. A tool was supplied with the mixer to do this, it is the blue part priced at £ 7.84 I linked to in my earlier post. You don't need the correct tool, I use a pair of circlip pliers inserted into the holes and turn that with a spanner. If they are very tight you can use a hammer and old screw driver to start turning them, not nice but effective.

    4. Make sure the stainless steel filter comes out with the piston assemblies.

    5. Use a 10mm Allen Key (a plastic one was supplied with the shower but is not much use so best to use a good one) to undo the small valve assembly at the back of the valve, make sure the Allen Key is a good fit, if you round this brass part off you have a real problem!

    Fit new valve assemblies and pistons, refit red and blue indices, reassemble the plastic ring and brass nut, refit temperature limit stop and control knobs and you are all done.
    • Winner Winner x 1
  7. Carl1

    Carl1 New Member

    Thanks very much, Shower Engineer. Managed to replace the cold piston assembly, but for the hot, the screwdriver trick was effective only at damaging two screwdrivers. I also tried the point of a chisel, but to no avail, though did not want to completely destroy the surface. There seemed to be some kind of oily substance on the surface of the hot piston assembly, maybe left there by the last person to look at it. In any case, two questions: Does the hot piston assembly have the usual right-handed thread, or is it reversed for some reason? Any other suggestions?
  8. Shower Engineer

    Shower Engineer Plumber

    Yes it is a normal thread on the hot piston, turns the same way as the cold one.
    You could drill the two existing holes slighyly larger so you could place the points of a pair of long nosed pliers in the holes. You can then turn the pliers with a shifting spanner.
    If you try this be very careful not to damage the body of the shower as that can't be repaired.
  9. Carl1

    Carl1 New Member

    Thanks. It seems the leak has stopped and the shower temperature is more stable, so I'll declare victory at this point and leave the hot piston assembly for the future.
  10. Shower Engineer

    Shower Engineer Plumber

    Glad it is sorted, lucky it was the cold piston causing the issue.
    The piston assys do not effect the temperature so hope that is ok.
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    1. bristan mixer shower leak

    2. i have change my shower cartridge in my bristan exsoped still leaking