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Grey Water Recycling


Grosey

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About £400 worth of parts in that lot...

 

Header tank looks like a Polytank header tank, pump is a chinese stainless submersible, and the filters are pretty standard stuff.

 

The underground tank looks GRP, but it also mentions a Bromine dose which appears to be using a tee'd spur that recycles some of the water back to the tank. I would query the capability of the system not to either under or over dose based on that solution, and also the maintenance of the underground tank components.lA

 

Also makes no mention of BS 8525-1:2010 which is the standard for greywater systems.

 

Greywater is a headache as it needs a full set of additional pipework running alongside the ordinary soil system which will double the price and complexity. It also means your soil system isn't getting as much flow - this sometimes helps to keep pipes clean and free running so make of that what you will...

 

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We looked into something like this early on in the design process and were very surprised at how consistent the advice we got from people involved with, eg, passivhaus and the AECB, was.  To a person, they said that you'd never get your money back given the costs of supply, installation, extra pipework, and ongoing maintenance.   

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On economic terms it makes no sense at an individual house level IF you already have mains water supply and public drains available - the water authority are, in effect, processing grey water and putting it back into the water cycle, but on a massive scale and hence at very low unit cost.

 

I think this is for people who are either off grid or are really single minded about saving water - though the cost to environment of all that extra kit might reduce any perceived environmental benefit.

 

I decided, early on, to focus my effort and money elsewhere.

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I've looked at rainwater instead as its easier to process.

  • Filter at the gutter to get all the big stuff out - we have trees so gutter hedgehogs are a no-brainer
  • Filter at the downpipe to get the sediment out - Wickes do a really good settlement style filter
  • Buried IBC tanks under the patio to provide a lot of storage and settlement for fine silt (tank 1) 
  • Final filter at the tank is then on the pickup for the pump - can be backwashed if needed without opening the tank.
  • Jet Pump with an auto switch to provide the pressure into the house sat behind a 5um filter and a charcoal filter 
  • No automated top ups to the tanks, just a simple level switch in the tank and a hose into the closest downpipe gully

Total additional cost for that lot is about £400, equates to saving around £130 of water a year so it has a short payback for me.

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Just thinking, and asking people who know more to knock holes in my thoughts.

 

Rather than running 2 pipes to everything, are there ways to make it more cost-effectiive.

 

AFAICS greywater can be reused directly (ie unprocessed) in certain applications such as garden watering.

 

So could the high volume things - bath, sink, washer, shower - be connected directly to the grey water tank, and not connected to the normal outlet, and the water can then be used as needed.

 

Equally could the rainwater be sent to the same place to save expense on the outside.

 

Is there a problem with applying a bit of filtering to the grey water by running it down through a gravelled drive, or a drainage field under the garden, with a collector at the end?

 

The biggest problems I can see are that this is potentially not dot-and-tittle clear enouigh for any British Standard, and consumer resistance from house purchasers.

 

Ferdinand

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8 minutes ago, Grosey said:

Ideal, that pretty much decides it for me. 

 

Any ideas if whether treated rainwater would be suitable for use in a hot tub?

 

People swim in natural pools, and these are often full of ex-rainwater...

Edited by Ferdinand
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27 minutes ago, Ferdinand said:

 

People swim in natural pools, and these are often full of ex-rainwater...

 

Yes, just wondering about any issues there may be with running rainwater through the pump/filtration and heating elements of a hot tub?

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None at all - you may need to adjust your chemical routine though and test it more. 

 

I'm planning a 5um filter - more then enough to take the rubbish out. Your filter on your pump on the hot tub will let sand though I expect so don't panic ...

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Not convinced at all about grey water recycling.  Strikes me as being problematic (and expensive) to avoid nasties.  Rainwater harvesting seems a better bet.  Until such time as Scottish water moves to metering, there is absolutely zero incentive for us to adopt rainwater harvesting.  Living on an island which sustained the water needs of an additional 100000 servicemen (and additional visiting ships) during WW1 and WW2 without problem, leads me to believe that water shortage isn't really an issue for us.

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I on the other hand live in South West Water's area... Quite a different story :)

 

I do do actually happen to have running water from somewhere right past my boundary, I may have to look in to harvesting that. 

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