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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorbardo
    • CommentTimeMar 18th 2020
     
    Hi all, I am about to install a cold water supply in our new build home and looking at what pipe to use. I would use copper however that's not possible without many underfloor joints which I'm avoiding. The options are hep type pipe and polyethylene PEX. Both are Wras approved however I have read posts from the USA saying that some PEX can leach chemicals and odors. Can anyone offer some guidance based on personal experience?

    Cheers,
    • CommentAuthorgoodevans
    • CommentTimeMar 18th 2020
     
    Do you have anything more specific than the advice you received in this thread?

    http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16385
    • CommentAuthorbardo
    • CommentTimeMar 18th 2020
     
    Posted By: goodevansDo you have anything more specific than the advice you received in this thread?

    http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16385" >http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16385


    Your advice and photos as well as those from Peter from Hungary helped me decide on the pex system for our hot water and rads needs. My new question concerns cold water and the best pipe for chemical free water quality.
    • CommentAuthorgoodevans
    • CommentTimeMar 18th 2020
     
    OK - I would say I have not detected any taste or smell problems with the pex-al-pex / multilayer pipe I used. And I would recommend the multilayer over the regular plastic pipes as it stays bent, and doesn't spring when you are trying to handle it.

    Obviously the pex may leach nasties (shouldn't much if it is supposed to last 50 years), but in it's favour would be the long lengths of smooth pipe resistant to harbouring bacteria. However - getting quality information on the leaching properties of any type/brand/batch of plastic pipe will not be easy and is likley to be subjective, out of date, and possibly unreliable.

    If you have to go for plastic - get a wras approved brand and go for a multilayer pipe for ease of install. Finally, after installation is complete, flush the drinking water pipes for a couple of minutes each day for a week or two before drinking if you are particularly concerned.
    • CommentAuthorCliff Pope
    • CommentTimeMar 19th 2020
     
    Surely in normal use the water will not lie for long in the pipe, but be turned over very quickly?
    Also very little of the water will be drunk, in between each glass you drink, gallons will have flushed out the pipe supplying loos, baths, showers, washing, etc?
    • CommentAuthorgoodevans
    • CommentTimeMar 19th 2020
     
    Yes - I agree - but different people have different levels of anxiety to unseen and seen dangers - It's no good saying it's WRAS approved, its safe. But is is worth pointing out that there maybe unseen benefits of different options also.

    Personally I'm fairly blasé wrt these types of concerns - if for example the effect of PEX pipes on health or taste is large or measurable many people would already be complaining, if it's not significant there are many other choices in life I could be making that would have a bigger effect.
    • CommentAuthortychwarel
    • CommentTimeMar 19th 2020
     
    Given the feed to the house from your water company is almost certainly either a plastic or plastic lined metal pipe, what difference is it going to make.
    • CommentAuthorbarney
    • CommentTimeMar 19th 2020
     
    Personally speaking, I'm not too bothered by minute quantities of phenols etc leaching out from most plastic pipe types - although the quantities are measurable and are raising some concern throughout the EU

    What does bother me about all types of plastic pipe is the ability for the pipe to cultivate a biofilm on the internal surface - and that's pretty horrible stuff from a water hygiene perspective (and almost impossible to eliminate).

    Based on my experiences in Germany, I would opt for light wall stainless steel pipe for all of my domestic plumbing - and for any wet heating systems. It's simple to use with machine pressed fittings, light, clean and hygienic

    I note however the OP can't install rigid tube lengths (although I do have to wonder why there's a problem in a new build residence)

    Barney
    •  
      CommentAuthordjh
    • CommentTimeMar 19th 2020
     
    Posted By: Cliff PopeAlso very little of the water will be drunk, in between each glass you drink, gallons will have flushed out the pipe supplying loos, baths, showers, washing, etc?

    It depends on which piece of pipe you're talking about. The mains feeding the whole house, sure. The pipe leading to the tap that you draw your drinking water from, not so much.

    Posted By: barneyWhat does bother me about all types of plastic pipe is the ability for the pipe to cultivate a biofilm on the internal surface - and that's pretty horrible stuff from a water hygiene perspective (and almost impossible to eliminate).

    Even copper allows biofilms after a while, I believe. I think we rely more on the chlorine in the water and on avoiding deadlegs in the plumbing, plus heating water of course.
    • CommentAuthorbarney
    • CommentTimeMar 19th 2020
     
    Sure - but we don't heat the cold water for pasteurization (we often don't heat the hot water beyond 70C anyway), copper is better than plastic as it's naturally anti-microbial, but it also loses copper ions.

    There are plenty of studies that show SS would have the least rate of growth of biofilms - although there is no system that eliminates it in normal potable grade water from a utility mains

    It's also common for whole house filtration for chlorine - so we knock residual out at point of entry to the house

    Good design is essential - personally speaking I plumbed the cold feeds such that the last outlet is the most used and the legs off that run are as short as practicable - and the pipe is well insulated and not close to any heat source (like the HWS and heating lines)

    Regards

    Barney
  1.  
    Posted By: tychwarelGiven the feed to the house from your water company is almost certainly either a plastic or plastic lined metal pipe, what difference is it going to make.


    So much this.
    • CommentAuthorMike1
    • CommentTimeMar 19th 2020
     
    Posted By: tychwarelGiven the feed to the house from your water company is almost certainly either a plastic or plastic lined metal pipe, what difference is it going to make.

    +1 (unless you dig a well...)
  2.  
    Our last place had a well, with 500m of asbestos pipe running down to the house...

    Best tasting water I ever drank.
    • CommentAuthorGreenPaddy
    • CommentTimeMar 20th 2020
     
    Some things I've seen that have been swimming around in borehole water samples, and the treatment units, you would be able to "chew" them, never mind "taste". :sad:
    • CommentAuthorgoodevans
    • CommentTimeMar 20th 2020
     
    Do you actually mean swimming (as in tails, fins, legs) or is it the more passive form of the word swimming.:shocked:

    I would expect to see some organisms at the microscopic level (swimming with cilia/flagella) - but in usual quantities not chewable.
  3.  
    We fished a few frogs out of the well head tank from time to time. They'd started out by swimming, but then couldn't climb out... We never worked out how they got in.

    Neither could the previous owner, who had lived there since the 1950s and is still going strong, now in his 90s and moved into a bungalow.

    My point is, people are more evolved to drink 'biofilms' than modern society gives us credit for! It's not natural to drink sterile water.

    Having said that, we did install a UV lamp, so the cillia had stopped flagella-ing by the time we drank them.
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