My pond water level keeps going down. What can I do?

Pond water level dropping

A very regular enquiry to our office at The Pond Guys is that the customer is experiencing a dropping water level.  There are many reasons that can cause this and so, firstly, it is best to carry out a few simple tests which help to pinpoint the problem.

Blocked Filters and Waterfalls

If the pond suddenly starts going down quite quickly and you have moving water as part of the pond, then very often the cause is linked to this.  Firstly, check that any installed filtration system is not blocked and overflowing – this is surprisingly common!  A filter needs cleaning every month, especially during the summer when algae blooms can overcome and block a filter quickly.

Then, if nothing unusual is found in the filter, check all the waterfalls and streams, paying particular attention to where the water flows from one section to another.  These ‘pouring lips’ can often trap twigs and leaves, which can limit the water’s exit and raise the level of the water prior to the blockage.  If the stream normally runs with the water level quite close to the top, then a small blockage can often cause the water to flow over the side of the waterfall or stream and into the garden rather than back to the pond, causing the water level in the bottom pond to drop.

I’ve checked this, but found nothing?

If neither of these prove to be the case, then if you have a filter and/or stream, the next course of action is to turn off the pump powering this for a couple of days.   If the water then stops going down, then we know the water loss is occurring somewhere in the system linked to the pumping system.  This will mean either the hose transporting the water has been damaged, or that the filter or waterfall is letting water out.  You can then focus your attention on these sections to see where the water loss can be occurring and fix it.

If during the above test your pond water level was still going down even with the pump turned off, or there is not a pump installed in the pond, then this means that the problem is then with the actual pond or lining.

I turned the pump off and the pond still lost water?

If this is the case, there are two common reasons.  Firstly, if the pond has a natural edge that overhangs into the water (grass, planting) it is worth trimming all of this back so that it is just above the water level in the pond, and nothing touches the water.  We have found many instances where the plants or grass have grown as a mat, hanging down into the pond.  These then act like a sponge and can ‘suck up’ surprisingly large amounts of water into the surrounding ground, meaning the pond loses water.  Cutting back the vegetation will stop this immediately, and so it is worth carefully checking all around the pond, especially if it is large, as roots can grow down the folds of a flexible liner and become quite matted whilst being difficult to see.

If none of these solve the issue, your pond may actually have a leak!  Unfortunately, this is the ‘dreaded’ one!

If this is suspected, leave the pond to go down for a few days until the level stabilises.  Normally the leak will tend to get slower as it gets nearer to the hole(s) in the liner, and so it is worth giving this a few days to stabilise.  Once it stops going down, efforts can be concentrated around this water line to see where the damage is.

Once the hole is found, then it can be decided whether a repair can be undertaken successfully.  Depending on the type, patching a liner can be successful, but more often than not we would recommend replacing the pond liner.  This is because if a liner is leaking, at this stage we do not know whether it is one or multiple holes. Therefore, you could end up patching three holes when there are in fact four, meaning you do not successfully cure the leak.  The other reason relining can be preferable is that it enables you to check why the hole developed in the first place.  The issue could be caused by a root from underneath the liner penetrating through, in which case patching the hole will be a very short lived repair.  In this instance, replacing the liner allows you to access and rectify the underlying problem, preventing it from reoccurring.

If you find yourself with the predicament of a leaking pond, please feel free to ring us.  We are more than happy to help and pass on our years of experience of ponds!

The Pond Guys are a pond installation and maintenance business based in Surrey, with teams covering London and the South East.

We are specialists in all types of ponds from ‘state of the art’ Koi ponds through to tranquil water gardens and water features.  We can help from initial design and construction through to servicing and maintenance, upgrades, filtration systems and everything else you could require

Do get in contact for any help and advice, or indeed if you need help with any aspect of your pond or feature.