Evaporation

Evaporation is the most normal and common cause for lost pond water. During the warmer summer months, water evaporation is typical and often overlooked as the reason. It's not uncommon to lose between 2-3 centimetres of water each week in hot weather. This rate is variable and can even be increased if your pond is especially shallow or situated in full sun, lacking shade from plants.

Quick Facts:

  • Caused by: Hot weather
  • Symptoms: Gradual and steady loss of water, dry ground surrounding the pond
  • How to fix: Top up regularly with dechlorinated water and provide more shade

Evaporation typically causes a steady but gradual drop in water levels, without the surroundings of your pond being wet. Topping up the lost water regularly is all that's required to resolve this. Be sure to treat any tap water with a dechlorinator before adding it to the pond, preventing chlorine from harming your fish.

For a long term solution, floating or marginal plants can provide shade, reducing evaporation in future. Monitoring the water chemistry is important when topping up regularly, especially in heavily stocked ponds. 

Try our pond water test kits for peace of mind while topping up your pond.

Water feature problems

Rapid or irregular loss of water can be a sign of issues with your pond equipment. Water features, including waterfalls and fountains, are a common cause. Sometimes they are not set up to return all water back into the pond. If the angle is even slightly off or the returning water splashes too hard, you may be unintentionally losing water around the edges.

Quick Facts:

  • Caused by: Height or angle of the feature directing water out of the pond. Excessive splashing or loose connections
  • Symptoms: Wet patches surrounding the outside of the pond, no water loss when the feature is off
  • How to fix: Adjust the height or angle of the feature, make sure all connections are secure

Garden pond fountain feature
Water features can cause loss of water if they are angled or installed incorrectly

Make sure to check all of the return points to be sure that the water flows smoothly into the pond. Splashing, overspray, or wet patches surrounding your pond, is typically the way to confirm this cause, but turning off the feature temporarily can allow you to determine this. It's worth adjusting the height or angle of your feature to easily resolve this.

Filtration issues

Your pond filter could be the cause of the water loss. Over time, clogging in the media can cause an overflow. Water may leak out of the box unit instead of returning to the pond, causing your water level to decrease gradually. If you notice your filter is spilling water, rinse your sponges and any other media in old pond water to remove clogging.

Quick facts:

  • Caused by: Clogged media, pond pump too powerful for filter
  • Symptoms: Overflowing filter box
  • How to fix: Rinse media, check flow rate of filter and pump matches

It's always worth checking the pipework too. Inspect all of the hoses and connections carefully for cracks and loose fittings, especially at joints and couplings.

Overflowing can be a sign that your pond pump is actually too powerful for the filter. This is because the pump is delivering more water than your filtration unit can handle. If your pump has an adjustable valve you can reduce the flow, or you may consider upgrading your filter to better suit the flow required for your pond's volume. 

Pond filter box situated at the side of a garden pond
Loss of pond water sometimes points to a clog in the filtration system

Bottom drain and submerged leaks

Water loss can occur below the surface of the water in ponds with a bottom drain. These drain systems can be diagnosed as the cause if you're still losing water after ruling out evaporation and filtration issues.

Quick facts:

  • Caused by: leaking bottom drain
  • Symptoms: still losing water after ruling out other causes
  • How to fix: Full or partial draining of the pond and sealing the bottom drain

Bottom drains require watertight seals. If you suspect there may be a leak, you'll likely need to drain the pond to gain access for repairs, either partially or fully. Unfortunately, this is not a quick fix while prioritising the welfare of your fish. Make sure to have a temporary space for them to occupy if you need to drain your pond.

Pond liner edge issues

Sometimes ponds lose water simply due to the pond liner slipping out of position. This is very common at the edges where soil and rocks may shift, often due to heavy rain or wildlife climbing in and out.

Quick facts:

  • Caused by: Liner slipping due to harsh weather or wildlife
  • Symptoms: Exposed, folded back, or dropped liner and damp soil surrounding the edges of the pond
  • How to fix: Re-position and secure the liner with rocks or edging materials

If you notice a section of your pond liner has folded back or dropped slightly, you'll find that water can escape from here. Inspect the edge of your pond for damp soil or exposed liner. Finding this early can allow for correction by re-positioning the liner and securing it with rocks or liner edging materials to prevent this issue reoccurring.

Garden pond liner being adjusted neatly at the edges
Small adjustments to the liner may be all that's needed to stop your pond draining

Tears or punctures in the liner

If you've ruled out all of the other issues and still notice a drop in water level, damage to your liner is likely the issue. Fortunately, it is easy to locate the rip or puncture by monitoring the level that the water drains to. The height of the hole will be where the water stops.

Quick facts:

  • Caused by: Damage to the liner
  • Symptoms: Water draining and stopping at a specific level. Damp ground surrounding the pond
  • How to fix: Liner patch kits or relining the pond

Once the water has reached the level where it stops draining, carefully inspect the liner above the waterline. Small punctures can be hard to spot, but even the tiniest holes can drain significant amounts of water over time. 

Minor tears and holes can be repaired with a pond liner patch kit and sealant. Make sure that the section of liner you are patching is clean and dry before applying the patch or sealant. 

For larger holes and tears, a section of the liner may need to be replaced, or even the entire pond re-lined. Using an underlay makes a significant difference in preventing punctures and tears in your liner, so be sure to install one if you need to re-line your pond. 

If you need help relining your pond, take a look at our step-by-step guide here.

Laying a pond liner underlay in a dug out garden pond
Always lay an underlay first to protect your liner

Common causes of liner damage:

  • Sharp rocks and debris beneath or above the liner
  • Installation without underlay
  • Improper installation
  • Invasive plant roots
  • Animal interference such as dogs, herons, moles, or rodents
  • UV damage
  • Weather exposure
  • Natural wear and tear
  • Low quality liner materials

My pond is still losing water

If you're still noticing the water levels in your pond dropping after checking all of the common causes listed above, it might be worth considering professional advice.

Our pond experts are here to help via phone or email. Whether you need help with diagnosing the issue, general advice, or help with choosing equipment, we're here to help.