Water leak under concrete driveway: how to find / repair without ruining driveway

Forums › Home Workshop DIY › Water leak under concrete driveway: how to find / repair without ruining driveway

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#1828476 24-Jul-2017 15:06

kryptonjohn:

Easy enough to cut along imprint lines (is it imprinted as cobbles or pavers? But it will be min 100mm thick so if you cut it into large pieces they will be extremely heavy and difficult to move. Would have thought not too hard to just cut a couple of holes within the pattern then when done pour new concrete in and colour match/re-imprint to match.

The harder part is finding where the leak is - could be anywhere?

kryptonjohn:

If the driveway is quite new you should be able to get close and the difference will fade over time.

It looks like pavers. Yeah it would be super heavy, I doubt a person could lift them. You'd never be able to match the pattern or color unfortunately, but yeah over time probably less obvious.

MikeAqua:

Is the leak on the house side of the toby or the street side?

If it's on the street side the convention is (or used to be) that it's the councils responsibility to repair and reinstate. Those are the rules where I live anyway.

Certainly you can't patch concrete without it being obvious it has been patched - even little things like matching colour/aggregates etc are all but impossible. You normally need to re-pour the panel.

Toby side, our responsibility. There's not really panels, it was one long pour, but it does have cut lines every few meters.

neb

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#1828478 24-Jul-2017 15:09

kryptonjohn:
You should be able to prove the leak by checking the water meter before you go away for the weekend then checking it when you get back. It shouldn't move if the house has everything shut off.

I think the problem isn't so much proving there's a leak as locating it. When we had a leak under the concreted area out by the street the water guys drilled holes in various locations and used a dipstick and stethoscope-like probe to try and find it. Took them quite awhile to locate, and they ended up cutting out a section of concrete about 1.5 x 0.5m to get at it since it wasn't obvious exactly where it was.

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#1828502 24-Jul-2017 15:36

I had similar situation many years ago when Auckland water bill just bill once every two months, I expect the leak was start of the first month, so we have no idea until the second month bill arrive and shocked to see the bill, pretty much having 2 months of leaks without knowing at all and no leak visible at that 2 months.

Can't find the leak end up relay a whole new pipe and we have long driveway with two neighbors. Part of the driveway is fully concrete so when the new pipe reach the fully concrete area, we end up just hang the new pipe by the fence with a bigger pipe as a protector of outer layer of the new water pipe inside. If we would want to cut the concrete & lay underneath and reach to the house, it would cost way too much.

Insurance decline our claims. Watercare at that time happily cut 50% of our water bill cost at that time. The whole fix end up just get a small loan from bank to pay the whole expenses. Until today able to see the pipe hanging from the fence its a reminder to check the water meter from time to time to make sure no leak somewhere else.

Hope you able to get it fix with less cost. It's obviously not fun to deal it.

timmmay

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#1828525 24-Jul-2017 16:13

Putting in a new pipe is worth considering, if they can pretty much thrust from the street. We don't even really know where the current pipe goes.

I guess we wait until we get the letter from the council, then see where we go from there. We don't know if they'll say "we suspect a problem, you fix it, not our problem", or if they provide some kind of diagnostic help.

MikeAqua

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#1828530 24-Jul-2017 16:26

timmmay:

I guess we wait until we get the letter from the council, then see where we go from there. We don't know if they'll say "we suspect a problem, you fix it, not our problem", or if they provide some kind of diagnostic help.

You can get pipe inspection cameras and similar. I'm not sure what the smallest pipe diameter they work in is?

Mike

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#1828534 24-Jul-2017 16:31

There are companies specialising in leak detection who use sound-detection for leaks (presumably water main under pressure). More or less like stereo sound location to pinpoint position of a suspected leak, using transducers pressed on the ground. Can be very effective - but also can lead to false detection, from noises from joins etc in pipes.

If it's quake related, then an issue for some people in Chch was that EQC (or insurance if over EQC cap) were very reluctant to front-up and pay costs for such investigation. If you carried out an inspection and found no fault, then you bear the cost. If it was quake damage, then they'd pay the cost for repair and the cost for investigation. I gave up on my insurer - after a year or so of being told they'd "get around to" surveying our sewers and stormwater, I paid for a drainlayer with video gear to survey and write a report - about $250. Once presented with the report and a quote to repair (about $7k) then they agreed to pay the lot immediately - including the cost of the survey.

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timmmay

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#1828537 24-Jul-2017 16:34

MikeAqua:

You can get pipe inspection cameras and similar. I'm not sure what the smallest pipe diameter they work in is?

That seems to be more for larger waste drains than water pipes, but I emailed a company to see what they say. Thanks for the idea :)

mdf

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#1828549 24-Jul-2017 16:48

timmmay:
MikeAqua:

You can get pipe inspection cameras and similar. I'm not sure what the smallest pipe diameter they work in is?

That seems to be more for larger waste drains than water pipes, but I emailed a company to see what they say. Thanks for the idea :)

^^ This. Drain layers have a surprising number of tools and tricks. I think because digging is such a cr@ppy job they have an incentive to innovate (much less the - literal - cr@p atbth bottom of the hole...).

If you haven't already got someone, Shane (?) at drainspy seemed a good guy to deal with. This was years ago though.

kryptonjohn

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#1828565 24-Jul-2017 17:16

Fred99:

There are companies specialising in leak detection who use sound-detection for leaks (presumably water main under pressure). More or less like stereo sound location to pinpoint position of a suspected leak, using transducers pressed on the ground. Can be very effective - but also can lead to false detection, from noises from joins etc in pipes.

That would be interesting.

We once had a faulty phone line coming from the boundary mushroom into the house. The tech put an electrical device on the master socket in the house and that told him the distance from the master socket to the fault in the cable - pretty cool. Naturally it turned out that the cable fault was under a large concrete patio slab not so cool :-(

Can't see the equivalent working in a water pipe to find a leak as there's no boundary at the leak (unless the pipe was completely broken but then there'd be no pressure in the house).

timmmay

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#1828580 24-Jul-2017 17:45

I guess I wait from the letter from the council and see what it says. Based on that I may look into high tech options.

If anyone has any solid information on my 1/2/3 questions very interested to hear it.

mattwnz

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#1828600 24-Jul-2017 18:03

What if there isn't actually a leak at all, and you end up ripping up the driveway etc, and not even find where the problem is. Will the council reimburse you for all costs for making an error? How do they know that it isn't somewhere in the house, or an external pipe running to an external tap etc?

We have had leaking pipes before prior to getting our home replumbed, as we had the faulty black piping. However the council never detected any of the leaks when that was leaking, and I have seem them checking our toby from time to time with their sound meter thing. If you are on a hill, maybe they are scared that it could lead to a landslide.

As others have said, the best solution maybe to bring in a new line and hopefully bypass the drive. Although you won't know if there is a leak under it, it will at least mean you don't need to touch it.

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#1828622 24-Jul-2017 18:51

Do you have any idea what the existing pipe is made of? Some seem to fail without needing a specific event. That might affect your chances of insurance. It could be that replacing is the only sensible thing to do as the same fault could reoccur anywhere along the pipe.

What sort of toby do you have. Ours was replaced a while back with a black plastic box with a meter ready shut off valve. If you had the same it would be easy to put a test meter on the pipe.

timmmay

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#1828643 24-Jul-2017 19:22

I would independently verify before doing anything drastic, and look into replace rather than repair options.

The pipes I saw down there are copper, 10-15mm diameter was my impression. The water pressure from the street is very high, it needed a reducing valve before it went into the new high pressure cylinder.

Toby is a metal lid with a tap in it, a ways down. The driveway is built up about half a meter, because the section slopes. That could make it fun too.

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#1828749 24-Jul-2017 22:46

Just wondering - you can't re-pipe mains but above ground level can you? What if your property have many mature trees with crazy roots?

elpenguino

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#1828753 24-Jul-2017 23:04

kryptonjohn:

The tech put an electrical device on the master socket in the house and that told him the distance from the master socket to the fault in the cable - pretty cool. Naturally it turned out that the cable fault was under a large concrete patio slab not so cool :-(

Can't see the equivalent working in a water pipe to find a leak as there's no boundary at the leak<SNIP>

Surprisingly enough, the same idea can be used for water pipe leaks. I know this having done a minor repair for a bloke with one. He puts a transducer on 2 points aways apart and the gadget could estimate the leak distance inbetween.

TDR = time domain reflectometry

For the OP, definitely agree that bypassing the bad section is probably the best/cheapest idea. You might have to insert a junction point/manhole into your concrete as a place for this new feed to join to the old feed.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

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