The pond shape and area can be marked out with sand or a hosepipe, or better still a paint-spray to achieve the shape desired. The hole should then be dug, ensuring that the following elements are observed:
1. Water will always find its own level. The pond must be level otherwise the water will find its own level and expose the liner.
2. The pond sides should slope at about 45 degrees.
3. At 9 inches down from the sides a 12 inch wide 'shelf' should be built all the way round.
4. Continuing inwards from the shelf, slopes still at 45 degrees, the pond should be dug to a depth of just over 3ft.

At this stage extra digging to lay cables required for powering the filter, pump, heater and lighting should be done. For this purpose, the connection of a power supply (incorporating a circuit breaker) should be completed by a qualified electrician.

The hole should now be completely lined with a layer of newspaper followed by a 2-inch layer of soft sand, so that nothing from underneath will puncture the butyl liner. The liner can now be laid into the pool to fit the shape - but not secured. A little water should gradually begin to be transferred to the pool, and, as it fills, the weight of the water will help the liner fit snugly to the sides of the pond. Only when the weight of the water has weighted and pulled the liner well into the pond can it be secured firmly.

Once there is sufficient water in the pond the remaining exposed liner can now be covered with pebbles and stones (for the 'beach' effect), or folded and tucked well down into the soil (allowing for your 'Bog Garden' area). Turf can then be laid up to the edge of the pond, or soil put in the Bog Garden border (on top of a 2" layer of gravel to stop the wet soil becoming 'sour'). Don't forget to puncture a few holes in the Bog Garden section of the liner to allow a small amount of drainage.

The biological filter should be positioned next to the pond above the level of the water, preferably hidden from sight. The pump should be sited in the centre of the pond on a brick (to prevent dirt getting in). This will pump the water to the biological filter and allow the cleaned water to drain back into the pond.

Planting

The planting can be divided into four areas: - the borders surrounding the pond, the bog garden, marginal (banks and shallows) plants, and the depths.

Surrounding Borders
These plants need not necessarily be moisture-loving plants (as their roots will not necessarily be damp or moist), but care should be taken not to place any large number of deciduous plants too close to the pond.

Bog Garden
Care should be taken not to site a bog garden too close to any large tree roots as these will drain moisture from the soil. Plants here will love having their roots damp and moist at all times, appreciate a little shade and being out of the wind.

Marginal Planting
These are plants that will be based in water all the time on the marginal shelf approximately nine inches below the surface. Marginal plants are grown in aquatic compost within baskets/pots, top-dressed with gravel to retain the soil in the containers.

Depths
There are two categories here:
1. As above, but these plants will be positioned at the depths of the pond, and will usually flower at the surface.
2. Oxygenating and floating plants. A selection of two or three species will help defeat algae, keeping the water clear and oxygenated. They also provide good cover for fish and insects. However, as they tend to be rampant they will need some maintenance occasionally.