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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorRex
    • CommentTimeApr 25th 2021
     
    What ho one and all,

    Hindsight is 20/20 vision!!! There are a few things I wish I had greater foresight during the build. One of those is the installation of a few more external taps.

    Since the house is surrounded by gravel, I plan to bury (only a few inches but sufficient to prevent damage and hide it) a pipe from close to the current eternal tap, adjacent to the below ground brickwork to the desired location. Not a big deal.

    However, what would be the easiest and not overly expensive pipe option?

    I have thought about 15mm copper pipe but that will be more expensive and more work with solder and bends but perhaps, since it would probably not be empty during the winter, could cause freezing / bursting issues.

    Given that the chosen route does not get much rain and/or snow, would regular garden hose be OK, which is the ideal option?

    Thanks for your thoughts.

    Toodle pip
    • CommentAuthortony
    • CommentTimeApr 25th 2021
     
    It would work, I would use proper 20mm poly water pipe. Hoses would fail after a few years and will have high flow resistance
  1.  
    IMO it is a no brainer - use Polyethylene pipe (aka MDPE) and compression fittings. It is tough (but not lawn mower proof!) and will withstand repeated freeze/thaw cycles without damage.
    Regular garden hose won't stand much burying for long without collapsing and deteriorating.
    Polyethylene pipe is the standard water pipe and should be easily available along with any fittings needed - which are screw together without tools, just best to clean the ends of burs if you cut it with a saw to avoid damage to the o ring and make assembly easier.
    • CommentAuthorRex
    • CommentTimeApr 25th 2021
     
    Many thanks. Will investigate the 20mm MDPE. Seems to be some good deals on eBay.
    • CommentAuthortony
    • CommentTimeApr 25th 2021
     
    Can also get push fit fittings
    •  
      CommentAuthordjh
    • CommentTimeApr 25th 2021
     
    Posted By: RexI plan to bury (only a few inches but sufficient to prevent damage and hide it) a pipe from close to the current eternal tap

    The reason water pipes are buried deeper is to prevent frost damage. Infrequently used taps with water that stands for long periods are particularly prone. Are you prepared to isolate all the taps and open them whenever frost is likely? If not you may want to bury it deeper and/or insulate the pipe.
    • CommentAuthortony
    • CommentTimeApr 25th 2021
     
    Insulation won’t stop it freezing, marginally less likely, but freezing unlikely to damage non metal pipes
  2.  
    +1. You are unlikely to want to run water through a garden tap in freezing weather.

    Butt, have you considered collecting rainwater instead? :bigsmile: Better for plants and for the environment. I just got a heavily subsidised butt, stand, tap and downpipe connector via my water utility company. I then asked them for another and they sent that as well, so one for each side of the house.

    Edit: if you are set on having a mains tap, then put it where you need the water. Eg if it's for watering plants then put a standpipe tap in the middle of the veg plot or the back of the border, so you can use cans instead of a hosepipe, that way you'll know how much you are using.
    • CommentAuthorMike1
    • CommentTimeApr 25th 2021
     
    Posted By: Rexclose to the current eternal tap

    Not sure exactly where you're planning, but just in case it's not obvious, outside taps (or in this case the pipe supplying them) need to be protected by an indoor double check valve.
    • CommentAuthorrevor
    • CommentTimeApr 26th 2021
     
    Regulations demand that the pipe be 750 mm below the surface but buildings sites I have wandered onto where I have noticed the trenches pay scant regard to this, At my previous property my outside tap was fed from the house and I put in a "T" after the isolation in the house so could flush out the water in winter. I used a car foot pump. Whilst the pipe may not freeze your tap could. I don't bother where I am now as it hardly ever gets cold enough for long enough for pipes to freeze. But use MDPE blue under ground black if you have longish runs exposed to daylight.
  3.  
    Just a side recommendation. I've always found the standard brass 'outdoor' taps to be very unreliable and leak when on. I tried a different design that still relied on a rubber washer and they were prone to dripping in cold weather (I assume froze enough to slightly open the tap?).

    Just replace mine with these quarter turn ball valve, 'frost resistant' (they appear to have a plastic part that allows for some expansion) - not much more expensive and much better to use.

    https://www.lionshome.co.uk/home-improvements-taps/calido/
    • CommentAuthorRex
    • CommentTimeApr 26th 2021
     
    Gentlemen,

    Thanks for the various comments. The current external tap does feed off the mains, just after the internal stop-cock. It was all installed during the build and the BCO never had any comments, so not overly worried. The new' extension' will have a Hoselock fitting to connect to the external tap when SWMBO needs water on the other side of the house. It will not be a permanent connection, so not worried so will risk the non-installion of a one way check valve.

    Agreed that installing more taps(and a few more external 13A sockets) during the build would have made sense, but that did not happen.

    Regarding rainwater collection, totally agree, although I do get annoyed when viewing a planning application when the 'environmental' box is covered by a couple of water butts on the downpipe. Certainly better than nothing but really, only a box ticking token gesture.

    I do have a 6000 litre rain collection tank in the garden which is used for toilet flushing and garden/car use but with the current shortage of rain in leafy Surrey, it is virtually empty.

    Since no-one needs to use potable water for toilet flushing, in my humble opinion, it is almost criminal that the rainwater collection for that purpose is not a legal requirement on ALL new builds. The law should be changed.
  4.  
    Without wishing to hijack the thread too much, this has prompted me to contemplate an outside standpipe too.

    Our buried incoming mains pipe is about to be exposed by the workmen digging up our sewer which runs adjacent (but lower). We could tee off vertically from this point for a garden tap, however it would be branching well before it enters the dwelling and thus before the internal stopcock.

    From the above, am I right in thinking we'd just need to use some sort of double-check valve inline and located just after the tee? Are there any other considerations?

    The pipe is the blue MDPE barrier pipe, 32mm.


    Thanks in advance.
    • CommentAuthorRex
    • CommentTimeApr 26th 2021
     
    I don't know the legal details, but if you are intending to have potable water from a garden standpipe, surely there is little to no chance of contamination working its way back along the pipe?

    Regarding the stop-cock, there is always the stop-cock on the meter.
    • CommentAuthorborpin
    • CommentTimeApr 26th 2021
     
    Posted By: Doubting_ThomasWe could tee off vertically from this point for a garden tap
    I did exactly this during my build. You can get MDPE to brass tap fittings with an inbuilt double check valve. I put a stopcock inline below the tap (in fact this might be what has the check valve in it). MDPE direct to tap pretty much eliminates damage due to frost but I always turn off the stopcock and open the tap when the weather is cold as water in the brass tap could in theory crack it.
  5.  
    Posted By: borpinMDPE direct to tap pretty much eliminates damage due to frost but I always turn off the stopcock and open the tap when the weather is cold as water in the brass tap could in theory crack it.

    Sorry - not 'in theory crack it' but 'in practice will crack it' and I've got the taps in the scrap bin to prove it !!
    • CommentAuthorMike1
    • CommentTimeApr 27th 2021
     
    Posted By: RexI don't know the legal details, but if you are intending to have potable water from a garden standpipe, surely there is little to no chance of contamination working its way back along the pipe?

    On the contrary, without an adequate check valve it only takes a drop in the mains supply pressure to draw water back through the pipes, even if the quantity is small. Though in some circumstances - a big drop while you have a tap open leading to a siphon - the quantity could potentially be everything in your pipe.

    The consequences can also be serious. 20°C to 45°C is the ideal breeding temperature for legionella bacteria, and more-or-less the same temperature range that an outside tap / exposed pipe is likely to reach in the summer. You really wouldn't want an outbreak of legionnaire's disease to be traced back to your house.

    The maximum fine for failure to comply with the Water Regulations is currently only £1,000. But if you rent the house then potentially you could also be fined under other legislation (https://www.hse.gov.uk/legionnaires/legionella-landlords-responsibilities.htm). If someone actually falls ill or dies, I guess negligence or manslaughter charges might even be invoked.

    Posted By: RexIt was all installed during the build and the BCO never had any comments, so not overly worried.

    BCO's aren't responsible for ensuring your compliance with the law...
  6.  
    Posted By: Mike1The consequences can also be serious. 20°C to 45°C is the ideal breeding temperature for legionella bacteria, and more-or-less the same temperature range that an outside tap / exposed pipe is likely to reach in the summer.


    This was my principal concern. Is a non-return valve enough to stop this?

    I don't want to risk contaminating my drinking water for the sake of occasionally needing to water my plants..!
    • CommentAuthorMike1
    • CommentTimeApr 28th 2021
     
    Posted By: Doubting_ThomasIs a non-return valve enough to stop this?

    For safety you'll need an double-check valve mounted inside the house, plus (on the mains side of the check valve) a stop valve for servicing. On the tap side of the check valve a drain point is worth thinking about, if you can't drain it through the tap.
  7.  
    Mike1, thanks for clarifying. That might be where we come unstuck as we have some fairly heavy plumbed-in equipment just after the mains enters the house. Whilst we already have a stop valve there, I doubt there's the physical space to retro-install the double-check as well...oh well, hose-pipe through the window it is then!
  8.  
    DT, how about trying a water butt instead? You can get pumps cheaply, so you can power a hosepipe from the waterbutt if you are not into carrying watering cans. Lots of environmental benefits using rainwater etc etc

    If it doesn't rain enough (or your butt is too small, no offense intended!) you can top it up with a mains tap, the air gap will protect you against backflow into the mains, and you will have a sense of how much water you are using, which is one of the problems with hosepipes.

    I wouldn't connect my manky garden hosepipe to a kitchen tap though!
    • CommentAuthorrevor
    • CommentTimeApr 30th 2021
     
    Quite some time ago I had a discussion about check valves with some workers who were working on our mains in the road. I expressed a concern that I might end up getting dirty water from the farm across the road and whether they ever audited users to see if they had check valves. I was told not to concern myself as there was no risk, as the supply system ensured it could not happen. Whether this is general or just my area I do not know.
    • CommentAuthorowlman
    • CommentTimeApr 30th 2021 edited
     
    Posted By: revorQuite some time ago I had a discussion about check valves with some workers who were working on our mains in the road. I expressed a concern that I might end up getting dirty water from the farm across the road and whether they ever audited users to see if they had check valves. I was told not to concern myself as there was no risk, as the supply system ensured it could not happen. Whether this is general or just my area I do not know.




    I would imagine there are numerous check valves built into any delivery system, perhaps into meters for instance, just guessing.
    •  
      CommentAuthordjh
    • CommentTimeApr 30th 2021
     
    Posted By: owlmanperhaps into meters

    Not a very high fraction of properties actually have water meters. The pipes after the meter are the individual's responsibility, so nothing after can be trusted without auditing, and I can't think of anywhere upstream in the water company's pipes where check valves could be fitted?

    I suspect it all depends on the maintenance of continuous pressure to keep flows going the right way, or at least not catastrophically the wrong way. Plus the lengths of pipe involved.
    • CommentAuthorowlman
    • CommentTimeApr 30th 2021
     
    It has me interested so I'll do some checking with an engineer friend who works in the industry.
    • CommentAuthorEd Davies
    • CommentTimeApr 30th 2021
     
    Posted By: djhI suspect it all depends on the maintenance of continuous pressure to keep flows going the right way,
    That's my understanding. It's because that can fail that they're so keen to have air gaps or double check valves anywhere “wholesome” water comes close to mucky water, e.g., water in an open loft tank, in a bath or shower where it's been mixed with filthy humans or that's been standing for days in a hose. Those are both to prevent backflows within the home but also back into the public water supply.
    •  
      CommentAuthordjh
    • CommentTimeApr 30th 2021
     
    Posted By: owlmanIt has me interested so I'll do some checking with an engineer friend who works in the industry.

    I'll be interested to hear the results. I forgot earlier that even though most places don't have a meter, they do have a water board stopcock so it's possible there are check valves there. But the house next door to us just had a leak and the new owner couldn't find the stopcock. So he called the water board and they couldn't find the stopcock either*. So they just installed a new stopcock! But the owner insisted they didn't fit a meter :( Which surprised me because he's put up loads of bird boxes and things so seems to be 'eco' minded.

    * I wasn't too surprised. They couldn't find ours either the first time they came, despite having installed it only a year or so earlier.
  9.  
    Posted By: djhI suspect it all depends on the maintenance of continuous pressure

    We fairly regularly lose all water pressure, at least once a year. We are relatively high up the hillside, so when there is a leak or roadworks we lose water pressure first.

    On one occasion the water board chappie actually used our garden tap to vent the air out of the main, while he was refilling it from the other end with a tanker lorry.

    While the pressure is off, in principle any above-ground water we had connected, could syphon by gravity down into the main. Garden hosepipe dregs, anyone? :bigsmile: Hence the need for air gaps and check valves.

    Edit: the biggest risk is possibly the central heating system, which is pressurised by thermal expansion to greater than the mains water pressure. Like everyone else we have a short flexi hose connection in the filling loop, which is supposedly for creating an air gap but actually stays connected. I do make sure both the filling valves stay shut as I don't want to find rusty inhibited CH water in my morning tea.
    • CommentAuthorMike1
    • CommentTimeMay 1st 2021 edited
     
    For anyone interested in a classic case, check out the contamination of the village of Freuchie in 1995. A food processing inadvertently pumped sewage-contaminated stream water into the local water supply for four days. 765 people became ill and 5 ended up in hospital - fortunately all recovered. The ultimate cause was that a plumbing contractor had failed to install a backflow prevention device - the factory was fed from the stream and the mains, their water pressure was higher than the mains and the water meter was running backwards. The factory was fined £60,000. I'd guess that their insurers paid out more in damages.
  10.  
    The post by Mike1 is a very different situation to a garden tap. The factory evidently had 2 water supplies interconnected both pressured and without non-return valves between them. Very bad practice. Apart from the contamination that happened if there was no non-return valve on the stream system then a failure there could result in mains water out-flowing to the stream until someone noticed (perhaps by the size of their bill). I suspect the company would have billed the plumbing contractor as would the insurance co. - assuming the contractor had any money or 3rd party insurance. - Anyway such a situation would not happen with a garden tap.
   
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