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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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      CommentAuthorrichy
    • CommentTimeAug 18th 2012
     
    I want to experiment with using as much free water as possible in my house which borders open fields. It's just for fun really, but nice to think I could be self sufficient if the infrastructure crashes.

    My rainwater barrels fill quickly so I am thinking of getting a bigger tank and using that to provide water to a downstairs toilet and to feed the hot water system. The plumbing is easy to separate to allow me to do this.

    I was wondering about starting with a 1200L tank and pumping water from a borehole to top it up. The fields around my house are always pretty waterlogged, even in a dry summer so I reckon I wouldn't have to drill too deeply, I could have 12v pump and a solar panel to run it.

    So can anyone point me to any UK sites that have stuff like filters and well extraction bits and bobs. Any advice?
    •  
      CommentAuthorJSHarris
    • CommentTimeAug 18th 2012 edited
     
    Boreholes usually only extract water from underground aquifers, so it very much depends on the geology of the area where you live as to how deep you'll need to go, or even if there is any water at all under your land that could be extracted via a borehole.

    The water a borehole extracts is usually water that has taken a long time to permeate down to the underground aquifer, often many months, or even years. Generally most surface water doesn't make it down to underground aquifers at all, it either evaporates (directly or via plant transpiration) or it runs off via surface watercourses.

    Although you can drill a borehole and use it to extract up to 20 tonnes of water per day without the need for any form of licence, you cannot discharge surface water to it, in fact you have to take measures to prevent any contamination of an underground aquifer by surface run off. The EA need to be informed if there has been any potential contamination of an underground aquifer from surface run off, and you may well get into hot water with them over it, especially if other boreholes are pulling from the same aquifer and suffer from the contamination.

    My case is probably a least cost one, as the greensand aquifer is only about 20 m down under a shallow chalk bed (in fact the borehole company reckon we'll get enough flow at around 10 to 15m down). This is unusually shallow for most of the British Isles, typically water boreholes range between 30 and 80m deep. The cost to drill, cap and fit a downhole pump for me is around £7,000. If I needed to go deeper the cost would rise, as they charge a fixed fee for setup plus a per metre fee for drilling.

    The pump power needed is probably marginal for 12V operation, as the cable losses would be significant at the high current needed to pump from depth. I've not seen any DC pumps, so for a solar installation you'd probably need an inverter to run the pump at a higher voltage.
    • CommentAuthortony
    • CommentTimeAug 18th 2012
     
    I sounds like you may be breaching all kind of regulations to me.

    Why not try for all water for toilet flushing first? Install underground tank, solar pump to a loft store as a first step?
    •  
      CommentAuthorrichy
    • CommentTimeAug 18th 2012
     
    Regulations? Well there are people getting jailed in USA for growing their own vegetables and storing rainwater.....miles from their nearest neighbour. Regulations are getting out of hand and I now apply common sense in there place.

    I see water as being a basic human right and would go to great trouble not to pollute anyone else's supply or poison my family.
    •  
      CommentAuthorJSHarris
    • CommentTimeAug 18th 2012
     
    <blockquote><cite>Posted By: richy</cite>Regulations? Well there are people getting jailed in USA for growing their own vegetables and storing rainwater.....miles from their nearest neighbour. Regulations are getting out of hand and I now apply common sense in there place.

    I see water as being a basic human right and would go to great trouble not to pollute anyone else's supply or poison my family.</blockquote>

    As I said above, if you abstract less than 20 tonnes a day (which is 20,000 litres, and enormous amount of water) then you don't need a licence, or even inform the EA or anyone else you're doing it.

    If you accidentally let surface water run off enter a borehole you are, potentially causing a significant hazard though, which is why it's very important that the borehole be lined and capped properly. The same applies to wells, and is one reason that old wells were often built with a brick or stone lining and a raised wall, sometimes with a roof.

    The main issue is with letting organisms from faecal matter and urine into the aquifer, from birds and animals. Natural breakdown on the surface and in the topsoil renders these organisms harmless fairly quickly, but there are no natural breakdown mechanisms down in the underground aquifers, so the organisms can potentially spread fairly quickly to other drinking water supplies.

    It's easy to minimise these risks though, any competent driller will line and cap the borehole and then all you need to do is ensure the top is kept clear from any potential run off entering it, including some form of flood prevention contamination provision.
  1.  
    I differentiate between wells and bore holes. A well as described by JSH above, lined with brick or stone will be dug and only collect or have access to surface water, even if it is collected at a depth of the first impervious layer. This water will typically be this years rain and subject to seasonal variation. The raised wall around it and the roof are to stop things falling in and the wall lining is to stop the hole collapsing. with this type of well there is no attempt made to seal the sides as it only has access to the first level water. It is not possible to dig a well beyond the first level water.
    A bore hole is drilled and as JSH said it must be lined and capped not only to prevent surface water entering the bore hole but also to prevent contamination between lower levels of water if the bore hole goes down further than the 2nd level.
    A depth greater than about 8m will need a submersible pump, shallower depths can use a surface pump.
  2.  
    I have a borehole which is 47m deep which is within a well which is 2.5m deep. The borehole is lined and will have submersible pump which will supply the toilet cisterns and the garden. I am hoping the BCO will allow the roof runoff to run through a rumbling drain across the front garden and then into the well which is 1.2m in diameter. There are three water tables the first being at 2.5m which is in running sand and extends down for 12m. I consider the ground to be the rainwater storage tank. The reason I have the borehole is because originally it was to be a deep bore soakaway and I was going to have a separate rainwater collecting tank but the plans were scuppered when we hit chalk and it was water bearing!
    •  
      CommentAuthorJSHarris
    • CommentTimeAug 18th 2012
     
    The advice I've had (I'm also on chalk) is that you must take precautions to prevent run off from entering the underground aquifer. Around here pretty much everyone's drinking water comes from the chalk aquifer, a mix of a lot of private boreholes and the local mains supply which also comes from boreholes. I even have a bottled spring water company about a mile away that draw their water from the same aquifer. The water company and the EA seem pretty concerned about the potential contamination issue, as relayed to me by the borehole company.
  3.  
    JSH, at the time, 2½ years ago, I asked the BCO about the deepbore soakaway and was told to speak to the EA. They told me to look at their ‘Groundwater Source Protection Zone’ maps and that there wasn’t a problem if we were outside the inner and outer zones. I was also told to look at their ‘Aquifer Maps – Superficial Drift Designation’ to ensure we were outside the ‘Principal Area’. They also later told us we could use water from the borehole for domestic use. As you say the usage limit is very large.
  4.  
    If the EA allow a deepbore soak-away and then say you can use the same level for domestic water IMO this shows a lack of thought and error of judgement and I would not want to use domestic water from the same place some neighbour had their soak-away
  5.  
    P-in-H, an architect friend told me that in our area it's quite common to have deepbore soakaways on plots that are too small for herringbone soakaways. I guess the EA think it's up to a borehole user to test the water but I don't pretend to understand the thought process of the EA. I don't know what type of soakaways neighbours use but I now have a reedbed system which the BCO is happy with.
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