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Rainwater harvesting instead of soakaway for new driveway

We're having a garage built and a new extended permeable driveway (35 sq m approx). This should have a soakaway at least 5m from any building or highway, which would mean at the bottom of the back garden. In between the driveway and the back garden is a stretch of concrete along the side of the house. I thought a more practical (and ecologically sound) solution would be to have a rainwater harvesting tank that could take the driveway run-off (and possibly also from house and garage roofs). 
Has anyone done anything similar and/or have any advice (including any recommended companies). I'm in the Brighton area. Thanks.

Replies

  • ABrassABrass Forumite
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    If you're sticking the water into a tank, what happens when it's full. That brings you all the way back to your need for a soakaway.

    But if your new driveway is going to be permeable, you don't need to shift that water anywhere. In that case it's just the garage runoff that needs to be dealt with. I don't know if it's possible for the driveway to also allow your garage runoff to permeate down but that may be pushing it.
  • edited 6 September 2020 at 8:03AM
    JKenHJKenH Forumite
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    edited 6 September 2020 at 8:03AM
    What are you intending to use the collected water for? The tank will collect everything that washes or drips off the car including road salt, horse muck and general road grime etc. The salt won’t be very good for garden plants but if you don’t mind dirty brown water you could use it for flushing the loo but not much else.

    edit: I jet washed my block paved drive for the first time in 30 years during lock down. Now its got more grass growing in it than my lawn. Nothing would grow in the salty oily sludge that I washed out.
    Northern Lincolnshire. 7.8 kWp system, (4.2 kw west facing panels , 3.6 kw east facing), Solis inverters, Solar IBoost water heater, Mitsubishi SRK35ZS-S and SRK20ZS-S Wall Mounted Inverter Heat Pumps, Nissan Leaf (plus some ICEs:) )
  • CardewCardew Forumite
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    There are many posts on MSE, and elsewhere, about rainwater harvesting and a commercial system is very expensive. even if you could save and use, say, 10,000 litres a year it would reduce your water bill by around £30
  • Thanks for your replies. 
    @ABrass - I'm also confused about the need for a soakaway if the drive is permeable, but the architect has included it and builder mentioned it too. I will double check! If I had a rainwater tank I was planning to connect it to soaker hoses etc for the garden & possibly have it connected up for flushing the toilet.
    @JKenH - from my preliminary research it seems there would be some kind of filter but I will investigate further.
    @Cardew - I'm mainly considering this as a pragmatic solution to the soakaway problem (& also to make good use of rainwater) rather than money saving, but obviously will think again if the cost is prohibitive.
  • edited 7 September 2020 at 5:27PM
    DiggerUKDiggerUK Forumite
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    edited 7 September 2020 at 5:27PM
    To justify going ahead with your project you need a use for the water, if you have no use then don't bother. 
    We have a large cultivated allotment area plus a lot of garden and have a high demand for water. As we are on water rates, not metered, we can use hose pipes to our hearts content, but by conveniently locating water barrels next to all out buildings, summer house and sheds we can fill 18x 50 gallon/200 litre barrels and make life easier than unreeling hose pipes and sprinklers every five minutes.

    Such barrels are up to a hundred quid new, so skips and freebies outside peoples houses is how we obtained them all, this is Money Saving Expert, not Money Squandering Eejit after all. If your a snob and don't like old barrels everywhere, then get posh ones from the garden centre for an arm and a leg..._  
  • @DiggerUK thanks for your reply. As I explained in my OP, the reason we're considering this is because we've been advised we need a soakaway for our new driveway, and it would be logistically difficult to site one in accordance with the requirement to be 5m from any building or highway. If it was just to collect rainwater then we'd be doing as you suggest and supplementing our existing water butts.
  • DiggerUKDiggerUK Forumite
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    "Advised"..?..if you needed one it would likely be mandatory. 
    If you do need one I reckon you may find it easier to connect to the sewage waste, if that is the case you could still add a water barrel..._
  • Reed_RichardsReed_Richards Forumite
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    I've looked into rainwater harvesting. 
    • A tank is not a substitute for a soakaway; you still need a soakaway for when the tank overflows (or perhaps you discharge the overflow into the sewer system).  
    • To send water to a tank you need to collect it in pipes.  I don't see how you can do that with a driveway unless you have gully at the side and a slight camber to direct the water into the gully.  Then you want an impermeable driveway.  You need to do something with the water off the garage roof, however.
    • Many properties discharge the rain that falls onto the roof into the sewer system.  You get a discount off your water bill if you don't do that but the onus is on you to claim the discount.  Perhaps this is no longer allowed, hence the issue.
    • Surely it is the garage roof, not the driveway, that is the problem.   
    Reed
  • I've looked into rainwater harvesting. 
    • A tank is not a substitute for a soakaway; you still need a soakaway for when the tank overflows (or perhaps you discharge the overflow into the sewer system).  
    • To send water to a tank you need to collect it in pipes.  I don't see how you can do that with a driveway unless you have gully at the side and a slight camber to direct the water into the gully.  Then you want an impermeable driveway.  You need to do something with the water off the garage roof, however.
    • Many properties discharge the rain that falls onto the roof into the sewer system.  You get a discount off your water bill if you don't do that but the onus is on you to claim the discount.  Perhaps this is no longer allowed, hence the issue.
    • Surely it is the garage roof, not the driveway, that is the problem.   
    Thanks for your helpful reply @Reed_Richards. Yes, I had misunderstood the information from the architect; thr soakaway would be for the garage roof not the driveway, which makes perfect sense.
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