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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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    • CommentAuthorjon
    • CommentTimeMay 29th 2008
     
    Who are the best companies for RWH systems and why?

    I've come across a few but have no way of differentiating!
  1.  
    Try Rainharvesting Systems Ltd www.rainharvesting.co.uk

    This UK business has been involved in this technology for arounf 14 years or so and they use very high quality German technology which has been developed over a good deal longer than that. ...These guys are experts!
    • CommentAuthorjon
    • CommentTimeMay 30th 2008
     
    Hi Graham,

    Thanks, I've come across these guys before: They certainly have one of the better sites. Anyone else?
    • CommentAuthorhaggis
    • CommentTimeMay 30th 2008
     
    I'd recommend WWW.REWATEC.CO.UK
    They also use German components and have "possibly" the largest slice of the European market with over 60,000 installed in the last 8 years.
    I'm a retired engineer about to start my first and last self-build bungalow and I tend to select "overkill" products which will last and last. Their tanks just have to be backfilled with gravel, as they are massively strong. I spent some time looking at several alternatives at one of the large self-build shows.
    Rewatec seem to use use different UK agents across the country.
    I made up my mind standing alongside one of their tanks. It is as they say "built like a tank".
    Hope this helps
  2.  
    why not do it yourself? there is no rocket science to rain water recycling and all of the components required are avilable to buy, even second hand on ebay.
    • CommentAuthorjon
    • CommentTimeMay 31st 2008
     
    Thanks Haggis: Looks a solid product

    Hi Adrian, I'm researching for a small estate so can't DIY it in this instance
  3.  
    I have a client with a desire to capture his rain and possibly grey water. Although some RWH systems could actually burn more C02 than they saves, in this situation topography and end use of water could allow us to avoid underground tanks and pumps so it could still be a winner.

    In this context the DIY option is not avavailable, so would any one care to add any names to the list or relate any +ve / -ve experiences..?

    J

    PS I wonder how big an above ground tank could be w/out the need to trouble those charming plannig officers...?
    • CommentAuthorjon
    • CommentTimeJun 25th 2008
     
    Depends a lot on whether or not you need a SUDs strategy for the site James: If you're trying to capture grey then the excess couldn't easily be diverted to a soakaway (if that's what you had in mind). May not be a problem if you have combined sewers locally. Otherwise, not sure I'd try to mix grey and clean (even if the grey were from vehicular areas)
  4.  
    I though the grey part would be a bit of a waste of effort

    J
    • CommentAuthorCWatters
    • CommentTimeJun 27th 2008
     
    When I last looked there were several different ways to do the switch over to mains when the rainwater runs low. One involved a valve mounted in the supply from the rainwater store to the house together with a sensor in the tank and a control unit. The other method involved a float valve low down in the the rainwater tank itself that topped up the tank with mains water when it got very low. I don't know if the latter is still allowed but I'd be concerned that if the valve fails you might waste a lot of mains water before it was discovered.
    • CommentAuthorEcoSarah
    • CommentTimeNov 25th 2008
     
    Hi Guys,

    I took Haggis's recommendation and have had rewatec out to go through my plans etc, and have been very impressed with their professionalism and quality. I'm also looking at a couple of other companies, has anyone had any experience with these tanks that have been cut in half to save on transport costs, i'm told they are easily clipped together and have a watertight seal that in the "lab" will last for 25 years. But I'm very sceptical about it! I'm not interested in the GRP tanks, so it seems a weigh up against rewatec and these split ones.
  5.  
    http://www.aecb.net/forum/index.php?topic=1227.0

    have a look at this link regarding , rainwater harvesting systems , are they good for the enviroment?

    water butts are a great idea
    • CommentAuthorJonti
    • CommentTimeJan 1st 2009
     
    Sometimes it appears that no matter what you do it is not better for the environment. Maybe the problem is trying to tackle the problem with old fashoined materials.
  6.  
    You can justify the costs of rainwater collection quite easily as the whole kit is cheap using a lot of used orange juice containers if you DIY.

    You could use a basic septic tank (around £500) and a submersible pump (around £50). Since if you are only using collected rainwater for lavatory flushing there's no requirement to filter it, but if you did want to use it
    for washing etc, then you should find a fairly simple filter system for under £100. Installation adds on a bit. The downpipes from the roof have to feed into the tank which overflows into the sewer. The bigger the tanks(s) the better as they may store enough through a summer drought.

    Water charges are reduced as less rainwater is going down the sewers. Your water charges are joint water and sewer. The water eventually goes down it. Using rainwater to flush toilets (which is 40%, or more, of total water use) reduces sewer use.

    The water bills should drop by 2/3 using rainwater collection.

    Rainwater harvesting when right, is well worth it financially, as it has a short payback period.
    The other items that have short payback are:

    1. The GasSaver on Condensing boiler flues - about 3 to 5 years. It mainly is used to boost flows and save gas with combis on the DHW. Use it to heat a thermal store when the boiler is always running the payback should shorter again. http://www.zenexenergy.com/ Alpha, Ravenheat, etc, make them under licence.

    2. Shower heat reclamation. http://gfxtechnology.com/ This also has a short payback period.

    So:

    a) Insulate the hell out your house.
    b) Make it air-tight as much as possible
    c) Fit rainwater harvesting
    d) Fit a GasSaver (check payback first)
    e) Shower heat reclamation drain pipe

    a) & b) reduce he heating system saving money. Direct money towards the above points first, then consider all other technologies. These are more cost effective than heat pumps, solar panels, etc.

    If a new build then design to passive solar as well.
    • CommentAuthorjon
    • CommentTimeFeb 18th 2009
     
    Very specific advice but I'm not sure I would agree with the priority list (the first two are dead right though). Who are you Water Systems?

    We went with Polypipe in the end, 12,000 litres
    • CommentAuthormheff
    • CommentTimeFeb 21st 2009
     
    All right, probably a really stupid question as I'm no plumber and descriptions of home-made harvesters sound simple but this is beyond my brains at this stage.
    Does it matter if the system is a closed or open system to have a rain water harvester?
    Mike
    • CommentAuthorwastetech
    • CommentTimeMay 3rd 2009
     
    If you don't filter the rainwater, then the water will contain leaves, bird faeces, moss, etc. which will form a decomposing sludge in the bottom of your tank and cause the water to smell. Thois is not the fragrance that you really want when you flush the toilet!
    Click onto http://www.rainwater-harvester.com as they have some very good 'all-in-one' and DIY systems.
    • CommentAuthortrule
    • CommentTimeMay 3rd 2009
     
    Here is another site:

    http://www.tankshop.co.uk/
    •  
      CommentAuthorjoe90
    • CommentTimeMay 5th 2009
     
    I fancy incorporating rainwater harvesting in my planned new build and have read previous threads on this subject right here. I plan simple DIY where possible because I do not believe in a lot of electrical control devices that need electricity and can go wrong. A question for someone out there who knows more about this than me."

    What is the typical cost of electricity to pump a cubic metre of rainwater rather than buy it from the water company ?".

    I firmly believe that water costs in this country are going to escalate in the coming years so any saving will only increase over the years.
  7.  
    some where on this site is the answer to your question ,
    do a search on water pumps and similar stuff
    I'll try and find it later
    • CommentAuthormike7
    • CommentTimeMay 5th 2009
     
    Posted By: joe90

    What is the typical cost of electricity to pump a cubic metre of rainwater rather than buy it from the water company ?".


    Hi joe90. I had a look at the cost of pumping harvested water, and it turned out to be completely trivial compared with the cost from the water co. Unless, that is, you do what I did, fitting a pump which would ooonly juuuust make it to the header tank when the store was low. I suppose all that stirring would have warmed it up a bit, at least. Fit a pump capable of 50% more or even double the maximum lift you need, and the cost will be pennies per m3.

    Many cheap submersible pumps deliver 5 to 7m head, which would do if your tank is above ground, probably. There aren't so many pumps delivering in the 8m to 30m head range but two cheapo pumps in line work well for me here.
  8.  
    •  
      CommentAuthorjoe90
    • CommentTimeMay 5th 2009
     
    Thanks guys, this is what I wanted to hear, cheap to pump your own
    • CommentAuthorwastetech
    • CommentTimeMay 14th 2009
     
    You must have an enormous roof for a 12,000 litre rainwater harvester - what is it for, a school or something similar?
    Roughly, the calculations for the size of tank allowed are between 5% and 10% of the annual rainfal in your particular region. This is to prevent the water going stagnant and to avoid the resulting risk of Legionaires disease, etc. A standard 4 bed house in the Midlands would require no more than a 4000 Litre rainwater harvester.
    For full details of exactly how to calculate the size needed visit http://www.rainwater-harvester.com
    • CommentAuthorDavidGoode
    • CommentTimeMay 27th 2009
     
    Thanks for the good info I've gathered from this site.
    A new question for you on this subject.
    I've not found any information on using harvested rainwater for use as domestic hot water. For a new build (and for meeting building regs) I know that the rain water must be treated to be potable with some sort of UV processing in addition to filtering. Is it worth going this extra step and if so what technologies exist for a self-build ?
    • CommentAuthorCWatters
    • CommentTimeMay 27th 2009 edited
     
    Posted By: wastetechYou must have an enormous roof for a 12,000 litre rainwater harvester - what is it for, a school or something similar?


    Perhaps they plan to use it to water the garden as well. We have a 6000L tank and have managed to drain it a few times watering the lawn and veg plot in dry spells.
    •  
      CommentAuthorjoe90
    • CommentTimeMay 30th 2009
     
    DavidGoode,

    I too plan to use rainwater for not only cold applications but bath/shower/washing machine use. Others have done the same and threads with this info can be found on this forum. I plan to harvest rainwater then heat it as it is required by using a heat exchanger on a heat store (heated by solar/woodburner/gas). This means I do not store heated rainwater (Legionella risk if not heated to 55 ish deg every 48hrs). I do not think this needs lots of technology just a practical brain to work it out. One problem with this plan is washing machines usually have cold feeds only (so you heat the water with electricity) and the fact that you need between a 5 and 10 meter head of water to get the water into the machine (they rely on mains water pressure to get past a water pressure valve).

    Previous threads have confirmed that it is much cheaper to pump rainwater up to a header tank than to pay for mains water. I think it would be easy to make a devise that admits mains water to this header tank if rainwater runs out or fails to pump from storage outside. Previous threads have also come to the conclusion that home made setups would only cost half what a commercial system would cost. Search this forum for rainwater harvesting threads.
    • CommentAuthortrule
    • CommentTimeMay 30th 2009 edited
     
    <blockquote><cite>Posted By: DavidGoode</cite>Thanks for the good info I've gathered from this site.
    A new question for you on this subject.
    I've not found any information on using harvested rainwater for use as domestic hot water. For a new build (and for meeting building regs) I know that the rain water must be treated to be potable with some sort of UV processing in addition to filtering. Is it worth going this extra step and if so what technologies exist for a self-build ?</blockquote>

    If you are going to use rain water for DHW then you might as well use it for everything else too. A pressure tank and pump are all you need to simulate mains water pressure for your appliances.

    For treatment, ultimately you will be responsible for the water quality therefore you need to assess potential contaminants and then design a system to match. UV filters, after physical filters, are a good way to disable bacteria and the like. There are also sand filters, reverse osmosis filters, charcoal filters each of which has an application depending on your collected water quality.

    Google on UV water filters, there are plenty on the market and they are simple to operate.
    • CommentAuthorDavidGoode
    • CommentTimeMay 31st 2009
     
    Some good feedback - thanks folks !
    • CommentAuthorCWatters
    • CommentTimeJun 1st 2009 edited
     
    Posted By: CWatters Perhaps they plan to use it to water the garden as well. We have a 6000L tank and have managed to drain it a few times watering the lawn and veg plot in dry spells.


    Speak of the devil. It's just run out again and we've only been watering the veg.
   
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