[roxie]

I have a very slow leak in our pond liner, made several attempts at finding the source but so far without any luck, any tips on how to locate the source of the leak ?

[James Kilkelly, was GPI.]

Is this pond on its own without a stream or cascade entering it, roxie?
Also does it contain any fish?
Is the pond created using butyl rubber, a fiberglass liner or smeared subsoil?

[roxie]

Pond has a high quality stretch liner (bitumen ? ) , it has a waterfall but this is turned off to ensure the leak is not a result of loss there, no fish.

[James Kilkelly, was GPI.]

This method requires a prolonged period of dry weather or else the covering of the pond from rain.
Just allow your pond to keep losing water, at some time it will stop and you can then go about locating the leak.
When it does stop, you have found the lowest part of the leak.

Check around the perimeter of the pond at the level that the water has stopped dropping for any visable holes or tears.
If none are visable, you must top up the pond with an inch or two of water.
Then gently pour a cup of milk as close to the center of your pond as you can get). It should be sucked toward the leak and you will be able to see the white milky trail.

If you see no trail from the centre, try adding milk to areas around the perimeter.
All this is best carried out on a calm day
If and when you find the hole, you can patch it with a liner patch kit available at or orderable from most garden centres.

Good luck in your search, let us know how you get on.

[roxie]

Many thanks for you tip it sounds a simple but clever way of getting to the source of the problem, I think the weekend is promising to be dry, I will let you know hot it works out, thanks again.

[GarethAustin]

GPI

genius idea about using milk.

[Rockworld]

Very good tip about using milk, personally i use condensed milk (made by a manufacturer with a well known flower in the title).
In liner ponds folds can be a problem area where leaks can be found, also if you have any pets which like to swin check the area where they enter and exit.

[John Robinson]

Hi, I have just joined this forum and found this thread.

I have a similar problem. My pond is leaking and stops going down at a certain level, suggesting a leak at that level. However, after a thorough search I still cannot find it, even amongst the folds (it looks like a rubber liner).

The pond is oval/kidney-shaped, about ten feet by seven feet and the surface drops by about two inches in a day, so I presume the leak is likely to be small.

Your suggestion of using milk sounds promising, but my pond has fish. I have two questions:

Will the 'milk method' harm the fish?

Is this method likely to work for a very small hole or holes?

If it is of any further help, the leak seems to have developed just after the big freeze we had a few weeks ago. Ice formed on the anti-heron(!) net and part of the water surface, but not in the centre where a fountain kept the surface clear.

I'd be very grateful for any help that would avoid my having to take out the fish and water and put in a new liner. I don't mind the work, but would hate to kill the fish!

[Rockworld]

Hi John, There have been a lot of pond leaks over the last few weeks, but all the leaks we have repaired are in PVC lined ponds, rubber epdm liner ponds don't seem to have a problem. This is probably because rubber liner can stretch up-to 4 times itself and hence is able to cope with water freeze and expansion.

To answer your question about milk, a small amount is all that's required eg an egg cup full so that will see movement towards leak.
Yes it works on small holes , it just requires a flow of water out at reasonable pace.
If this does not work then remember if the water always falls to the same level when leaking, that is point of leak. It is sometimes difficult to find so it may be necessary to drop water a further couple of inches to find easily. Its unlikely though possible to be behind folds.
If you still cant find leak then you should consider replacing liner with rubber liner that is 1mm thick.

[John Robinson]

Thanks Rockworld.

I think the liner is rubber and it feels quite thick. I don't know for certain because it was in when we bought the house.

I shall try the 'milk method', but I need to know first whether this would harm the fish (just ordinary goldfish).

[Rockworld]

A very small quantity is required, we have done it several times and found no problems with fish. For a definite answer you will need to ask your fish supplier directly, as they will be familiar with your exact fish.
To check if pvc or rubber liner, the main difference is that rubber liner stretches, it is thicker than plastic and it also looks similar to the tyre tube found inside a bicycle wheel.

[John Robinson]

Thanks again.

I think I'll try your milk procedure, as it sounds like it's safe for fish.

I did just have another good look and I can't find a hole. The water level remains at the same level, so it must be there somewhere.

Yes, it is almost certainly rubber, so I'll be able to use a patch.

In the meantime, someone told me that there is a liquid that can be put in the water and will search out and seal small holes. Unfortunately, he couldn't recall the name and I can't find anything like it on the internet.

[Rockworld]

That liquid sound like a great idea. Products exist for sealed vessels like bicycle tubes etc. I have never seen a product that will do this in a pond but if you ever find one please let me know.
(honestly don't think such a product exists yet but maybe some day)

[John Robinson]

Well, I'm pleased to say that I've found the leak, or my wife has with her beady little eyes. It had disguised itself as a drop of water, which is how I had missed it.

It is an oval-shaped hole, about one-eighth by three-eighths of an inch, not a crack or slit as I would have imagined. Anyway, I have now patched it and shall re-fill the pond tomorrow when it has cured. I'm glad for the fish's sakes that I didn't have to put in a new liner.

The thing that puzzles me is how a hole of this shape and size could have developed. I could post a picture of it if anyone is interested.

Thanks, everyone, for your advice.

[walltoall]

Anybody nearby own an airgun? anybody prod the pond while full with say a piece of wire?