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Thread: Does water run uphill?

  1. #1

    Does water run uphill?

    I thought I might seek the wisdom of those of you who know about land drainage.

    I have a groundwater problem in the driveway and had a French drain leading from the problem area into a pipe inserted into the wall of an inspection chamber within the garden. Well, although there was a steady trickle of water through the pipe into the chamber, there were still significant damp patches in the drive.

    I investigated last week and found the level of the perforated pipe under the drive is about 200mm below the discharge level into the inspection chamber. Water is therefore running uphill, presumably by a combination of capillary action and (resultant?) raising of the water table.
    I'm wondering how the drainage guy might explain this situation, especially as the money he charged could have got me a new Blaser. (Not that I would, of course...)

    Many thanks,

  2. #2
    I'm not entirely clear on this but are you saying that the outlet on the perforated pipe is higher than the depth at which the pipe is laid? Also re the damp patches on the drive that led you to have the work done to start with, did you ever discover the origin of this water?

  3. #3
    No, water doesn't flow uphill unless it's in a hydraulic jump, which doesn't happen in groundwater.

  4. #4
    No water cannot run up hill in an open circuit. What is probably happening is that when the pipe runs the surface level of the water is well above the outlet level. Water will drain down until it is at the level of the outlet.

    Fundamentally if you want a drain to work it has flow downhill all the way.

  5. #5
    Quote Originally Posted by Pine Marten View Post
    No, water doesn't flow uphill unless it's in a hydraulic jump, which doesn't happen in groundwater.
    or there is somehow some syphoning action going on somwhere

  6. #6
    If its a perforated pipe, then it will be at atmospheric pressure ( actually maybe slightly above, very slightly), as will the outfall. So, the water flowing in to the inspection pit is groundwater but the pipe away from the pit will be full and the water level above it in a straight level line to the inspection chamber, always assuming there is no backwater curve !
    No, water doesn't flow uphill, unless its pressurised. Here is cannot be (perforated pipe).
    The drain does not work (simply put) and I would ask a competent engineer to take a few levels and get the bloke back to do it properly. The water in the drive is another problem altogether, how high is the drive above the outfall? is the surfacing porous ? The amount of water you seem to be getting into the inspection chamber could be a leak, could be coming from the road outside or the house. Isolating the source of the water would be your first step as if its stopped, you may not have needed a drain. Difficult to be specific without sight of the problem and the outfall but the drain will not function without POSITIVE fall to the outfall from the head of the pipe, sorry to have to tell you.
    Last edited by kes; 06-06-2016 at 11:02.

  7. #7
    Gents,

    Sorry to butt in but as a Civil Engineer who designs drainage systems for a living the flow of water through the perforated pipe (or any pipe laid below its outfall) is down to hydraulic head and the resulting hydraulic gradient, some land drainage pipes will flow apparently uphill on the basis that a body of water will equalise in level.

    just to make matters worse ground water can actually flow uphill under trapped pressure but its very rare. Although we model this for the movement of contamination etc.

    For a demonstration have a look at the concept of a water level..

    Without anything else to go on I would get the contractor back to relay the pipe as with this situation your effectively creating a permanently we spot within the pipe and the bedding / trench alongside it, this could eventually wash the fines out from the supporting soils and you will end up with a long term settlement problem. your contractor / builder should have checked the level of the outfall before laying the perforated pipe? also is the run blocked or obstructed downstream of the new pipe as this can increases the head / water level in the upstream pipes accordingly as water tries to find a way around the blockage. and will eventually find a pathway through.

  8. #8
    jack and Jill went up the hill to fetch a pale of .................water !

  9. #9
    Quote Originally Posted by Bell308 View Post
    Gents,

    Sorry to butt in but as a Civil Engineer who designs drainage systems for a living the flow of water through the perforated pipe (or any pipe laid below its outfall) is down to hydraulic head and the resulting hydraulic gradient, some land drainage pipes will flow apparently uphill on the basis that a body of water will equalise in level.



    just to make matters worse ground water can actually flow uphill under trapped pressure but its very rare. Although we model this for the movement of contamination etc.

    For a demonstration have a look at the concept of a water level..

    Without anything else to go on I would get the contractor back to relay the pipe as with this situation your effectively creating a permanently we spot within the pipe and the bedding / trench alongside it, this could eventually wash the fines out from the supporting soils and you will end up with a long term settlement problem. your contractor / builder should have checked the level of the outfall before laying the perforated pipe? also is the run blocked or obstructed downstream of the new pipe as this can increases the head / water level in the upstream pipes accordingly as water tries to find a way around the blockage. and will eventually find a pathway through.

    With the greatest respect we are talking about a driveway - how much hydraulic head can you get ?
    There is no need to complicate matters or make this simple problem difficult. It cant be more than a 10m run laid nearly level for goodness sake - not as if you need hydraulic tables !
    From another degree qualified civil engineer, Member of the institution of Civils etc, qualified in drainage with 40 + years experience - which I didnt mention !

  10. #10
    Quote Originally Posted by kes View Post
    If its a perforated pipe, then it will be at atmospheric pressure ( actually maybe slightly above, very slightly), as will the outfall. So, the water flowing in to the inspection pit is groundwater but the pipe away from the pit will be full and the water level above it in a straight level line to the inspection chamber, always assuming there is no backwater curve !
    No, water doesn't flow uphill, unless its pressurised. Here is cannot be (perforated pipe).
    The drain does not work (simply put) and I would ask a competent engineer to take a few levels and get the bloke back to do it properly. The water in the drive is another problem altogether, how high is the drive above the outfall? is the surfacing porous ? The amount of water you seem to be getting into the inspection chamber could be a leak, could be coming from the road outside or the house. Isolating the source of the water would be your first step as if its stopped, you may not have needed a drain. Difficult to be specific without sight of the problem and the outfall but the drain will not function without POSITIVE fall to the outfall from the head of the pipe, sorry to have to tell you.
    From actual experience of professionally installing drainage systems I am inclined to agree.

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