How to dig a pond: the earthmoving method, from marking out to a liner-ready bottom

The location has been chosen, the shape drawn, and the liner is almost ordered. What remains is the work itself, the part that strains your back but nevertheless determines the success of everything else: an uneven edge, collapsing shelves or a bottom full of stones will cause problems for years. Digging a pond means first marking it out and levelling it, then digging from the outline toward the centre while respecting the shelves, and finally preparing a smooth, stable bottom before laying any liner.

Before the first shovel strike

A few checks can prevent unpleasant surprises. Contact utility network operators to find out whether there are buried cables and pipes. For a large body of water, ask your local council about any required formalities. And decide where the soil will go: this is the question most often overlooked, even though it determines the entire organization of the worksite.

Once removed, soil takes up significantly more space than it did in the ground, roughly one quarter to one third more volume depending on its composition. A pond of a few cubic metres therefore produces an impressive pile. Plan where to store it, a reuse project (mound, rockery bank, raising a flower bed) or removal.

Marking out, staking and levelling

Draw the outline with a garden hose or marking powder, then view it from the house and patio for a few days: this is the time to adjust the shape, not afterward. Then drive stakes all around it, about 30 cm outside the outline, every metre to metre and a half.

Set the tops of all the stakes to the same elevation using a laser level, a water level, or a long straightedge and a spirit level, moving from stake to stake. This reference plane represents the future waterline. On sloping ground, it immediately shows that you will need to dig on one side and add fill on the other.

The digging sequence

1. Remove the topsoil across the entire area and set it aside: it will be used for planting around the pond.
2. Dig the first terrace all the way around, at the depth planned for marginal and marsh plants.
3. Move down to the next terrace, leaving a step at least 25 to 30 cm wide.
4. Finish with the pit, where the deepest area will be.
5. Constantly check the depths from the stakes, using a straightedge and a tape measure.

Give the sides a slight inward slope rather than making vertical walls: they hold better, the liner fits the shape more easily, and a frog or hedgehog that falls into the water can get out via a gently sloping bank. Add a margin of 10 to 15 cm to the planned excavation dimensions for the sand bed and underlay.

Spade or mini excavator?

By hand, a small pond of a few square metres can be dug over a few weekends. Beyond that, renting a mini excavator makes all the difference: it can do in one day what would otherwise take weeks, and the grading bucket allows you to shape the banks neatly. However, finishing the terraces is almost always done with a spade, to create clean, well-compacted steps.

The edge: the step that allows no mistakes

If the edge is not perfectly level, the water will reach the surface on one side and leave the liner visible on the other. Check the height of the edge all the way around against the stakes, and correct it by adding or removing well-compacted soil. Then dig a small anchoring trench about thirty centimetres from the edge: the liner will be folded into it and held in place by soil or finishing stones.

This is also the right time to plan the pipe runs, the filter location and that of a possible skimmer: incorporating them now avoids having to tear up the banks later.

Prepare the ground before the pond liner

Go over the entire excavation and remove stones, roots, pieces of glass or brick. Cut the roots cleanly flush with the wall. Then spread a few centimeters of sand over the bottom and shelves, compact it, and lay geotextile felt over the whole area. Do not leave the excavation open for too long in the rain: the shelves will wash out and the bottom will turn to mud.

Measuring the liner once the excavation is complete

Do not order the liner until the hole has actually been dug. Measure the maximum length and width by following the bottom with a flexible tape measure, from edge to edge, then add an anchoring margin of approximately 50 cm on each side. This “following the profile” measurement is more reliable than the theoretical formula because it accounts for the shelves as they were actually dug.

Read also

Once the excavation is complete: Which liner should you choose for a pond?.

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Frequently asked questions

— Where should you start when digging a pond?

Start by marking out and staking: stakes set at the same height indicate the future waterline. Then strip the topsoil and dig the shelves before the pit.

— Should you rent a mini excavator to dig a pond?

For a small pond, a spade is sufficient. For a larger pond, a mini excavator saves a lot of time; finish the shelves by hand afterward.

— What should you do with the excavated soil?

Plan for it before digging: it takes up more volume once loosened. It can be reused to create a mound or embankment, or removed.

— What should you do if the hole fills with water while digging?

This is a sign of a high water table or very clay-rich soil. Dig during a dry period, pump out the water, and seek advice before installing the liner.

In summary

• Level-set stakes: they mark the waterline throughout the project.
• Keep topsoil separate, create the shelves first, then the pit, with slightly sloped sides.
• Plan for the volume of excavated soil, which is greater than you might imagine.
• Cleaned excavation, sand bed, felt, level edge: measure the liner once the excavation is complete.

Last updated: September 29, 2026.