Septic Tank and Foul/Rain water mixing

Discussion in 'Building' started by cooket3, 21 Dec 2018.

  1. cooket3

    cooket3

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    Hi, I have a septic tank and I found out my rain water and foul mix and end up in the same tank/drains. This has always been the case since I bought the property 7 years ago and since the drains were put in when the property was built.

    I've heard they shouldn't mix, however I bought the house like that and the estimated age of the property is 1890. I have also been told that if a property is over a certain age then this is ok.

    The septic tank is not over flowing, no water courses in the area and there are no wells

    I live in County Durham, if the rules are different to different areas.

    I would like an answer as I am having disputes with my neighbour (Who is also on the same private septic tank and pipes) and he is using this to try and get revenge for something I have not done, as I am middle terrace and the rain water off his roof goes into my drain and therefore says its my problem

    Thank You
     
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  3. Ian H

    Ian H

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    The rain water going into the tank would put more strain on the soakaway and reduce its life.

    I guess it could also drop more silt into the tank and the clean water could (but I don’t know for sure) upset the bacteria in the tank that break down the turds.

    Having said that if it all works fine then there is no reason for it not to continue working.
     
  4. StephenOak

    StephenOak

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    The restriction on mixing foul waste and surface (rain) water is, AFAIUI, to do with the public sewers. A lot of these were built decades ago and very little surface water went into them as it landed on permeable surfaces (e.g. gardens) and so soaked into the ground. Even it some did eventually drain onto the road and hence into the sewer it was a relatively slow process.

    With lots of gardens (mainly front but quite often back as well) having been covered for car parking there is a lot less permeable surface to soak up rainwater and these surfaces drain onto the road (and hence into the sewers) rapidly. So in times of heavy rain it is easy for sewers to be overwhelmed and discharge foul waste into rivers.

    The preferred option for surface water is now for it to go into a soakaway, which is what yours is doing.

    Many (most? all?) water authorities prohibit new connections of surface water to the sewers but there are millions of homes that were built before this changed and they are allowed to carry on as before.

    I am not sure what you mean by that. Surely a septic tank is supposed to overflow? Stuff comes in one end, the solids settle in the first part, liquid flows into the second part and, when that is full flows out to a set of pipes from which it drains into the ground.
     
  5. Ian H

    Ian H

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    I think he/she means it’s holding it’s correct level.
     
  6. Mottie

    Mottie

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    In our old house, the rain water and sink/bath water/toilet waste went into the same drain. The house was built in 1899 though, as was the rest of the whole estate it was on.
     
  7. lostinthelight

    lostinthelight

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    Even in 1970 when I first installed a septic system it was not best practice to discharge surface water into the tank.
    Septic sysems should be designed to slow the flow of effluent to a level that it can be treated and relates to the number of possible occupants of the property .
    Surface water speeds this flow resulting in untreated effluent reaching the final treatment area in the soak away .
    This untreated effluent cause black slime in the treatment medium which can block it forcing fluid to the groung surface or back up the drain pipes to the property.
     
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  8. Bosswhite

    Bosswhite

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    Have you had to have the Tank emptied if so who bears the cost or is it shared, also who is responsible for the cost of maintenance of septic tank ?
     
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  9. Diyisfun

    Diyisfun

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    StephenOak A soakaway & septic tank are not the same.
    ===

    I have a septic tank & we had problems with the drain field, had a new one put in, now no problems & a good septic tank should not need to be emptied.
    If rain water were running into one I would expect problems relating to solids not having enough bacteria as its being flushed away.
     
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  11. StephenOak

    StephenOak

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    Sorry, I do know the difference, I was not as clear as I might have been. I meant that surface water is supposed to go into a soakaway, and that going in to a septic tank and then draining in to the ground is doing essentially the same job.

    I thought that they just needed to be emptied very rarely, e.g. many years (a decade?) between times. After all there are solids going in to there.

    Maybe. What I meant was that for a septic tank the correct level (once it has been in use for a while) is just about to overflow, when a gallon goes in one end a gallon goes out the other end.
     
  12. Diyisfun

    Diyisfun

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    The solids break down & soak out, that's why no synthetic materials or bleach should be used.
    Yes a gallon in a gallon out, that's the problem with rain water going it, there's to much water going in at once.
     
  13. Bosswhite

    Bosswhite

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    It depends on much the septic tank is used as to the times it should being emptied , modern detergents do not help the bacteria
     
  14. tomfe

    tomfe

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    Not really, all you are doing is forcing poopy water into your drainage field. You might, under heavy rainfall, be forcing solids into your soak away pipes and blocking them.

    Foul and runoff should not be mixed as already stated, you'll never get the bacterial process up and running to break down the solids (toilet roll as well) and you'll end up having to have it pumped out much more often (yearly rather than every 10+ years)
    There is a bit of a con going on which the people who pump out septic tanks saying they need pumping out ever other year.
    They should not need emptying at all as long as you only flush what you're meant to.
     
  15. StephenOak

    StephenOak

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    @tomfe If you read what I wrote in context you will see that it is correct . The OP wanted to know about the restrictions on mixing foul & surface water. I was talking about the restrictions on discharging surface water into public sewers. Sending surface water into the ground is sending surface water into the ground and not into the public sewers, whatever route it takes. Via a septic tank is far from ideal but it does not contravene the (relatively recent) restrictions.

    That is clearly not all that you are doing, having the two connected clearly forces the surface water into the drainage field. That is written rather tongue in cheek as I am showing how one can twist what is written by taking something out of context.

    Or you might have no problem ever. It all depends upon the size of the septic tank, the volume of foul waste and the volume of surface water that is going into there.

    And I never said they should be. The OP is not proposing to merge the two, he has inherited that situation.

    You say that confidently but you don't actually know that. It depends upon the size & relative volumes.

    As the system is, according to the OP, working okay at the moment, has been doing so for the seven years the OP has been there and for however long previous people were there, I would guess that the solids are being broken down okay.
     
  16. lostinthelight

    lostinthelight

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  17. Hugh Jaleak

    Hugh Jaleak

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    Septic Tanks do need to be emptied, but the frequency depends on type and size of the tank, and it's usage. Whilst the treated liquor should leave the tank and be disposed of by whatever method is suitable, the solid matter will settle out and form sludge. It is this sludge that needs to be removed at periodic intervals, to prevent the tank clogging up, going septic, (despite the name), and ceasing to operate effectively, if at all.

    Rainwater should not go into a septic tank. It can cause peaks in the throughflow and upset the natural processes required within the tank to treat the effluent. Rainwater should be kept separate and ideally be discharged into an independent soakaway to prevent any backflow into the tank.
     
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