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Nov 15, 2021
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Stockton on Tees
Member Type
DIY or Homeowner
Hi has anyone dealt with or got any advise. We have been having problems for about 3 years with the hot water coming from a baxi 105 combi boiler. (We know it is the hot water as only filter on hit of mixer shower gets blocked) The filters on taps and shower are getting blocked with a sand like substance. We have had British Gas out on numerous times they can’t find anything wrong, however they have replaced the heat exchange just in case. We have had to replace the mixer shower 3 times and also the kitchen tap. We have had the substance tested and it is hydroxyapatite. How do we get rid of this. We are wanting to replace the bathroom and need this sorting before we buy another expensive shower Thanks for your help.
 
When you had the Hot water sample tested did you also have a sample of the cold water tested to check whether it's coming in from the mains outside?

It could be that heating the water containing hydroxyapatite is increasing grain size enough to get stuck in the taps, shower etc, whereas when cold it may just be passing through.
 
When you had the Hot water sample tested did you also have a sample of the cold water tested to check whether it's coming in from the mains outside?

It could be that heating the water containing hydroxyapatite is increasing grain size enough to get stuck in the taps, shower etc, whereas when cold it may just be passing through.
Yes it was the water board who told us what it was. However they are no help on how to get rid of it as it’s property specific. I have spoken to neighbours etc an they have no issue.
 
So if it's not in the water at all coming into your property, presumably confirmed by the water board, then you are managing to create it within the property, specifically in the boiler.

If so then the whole boiler should be the first thing to be replaced.
 
No definitely not hard water.
If you are sure about this, it's a mystery from where the calcium needed to form hydroxyapatite (calcium phosphate) is coming.

No one else on the estate has this problem.

Do they have the same type of showers / filters that you do? Are you sure that their water comes from the same source as yours?
 
Last edited:
I used a karcher water vac to clear pipes, opening a different tap for each run. Amount of ‘sand’ was an inch deep in the vac.
 

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