Building a Garden Pond

Ponds are a nice addition to all but the smallest garden and have the bonus of being great for wildlife in the area. With a bit of forward planning and the right equipment, this DIY job shouldn’t cause you too many problems. Just be aware of the safety issues of having a pond with small children in the household.

Planning Your Pond

The best position for a pond is on level ground, with some cover and in full view of the house (for safety). Some trees such as Willow, Poplar and Laburnum can poison the water in a pond if they are too close, so bear this in mind as well. Once you have found the best position, mark out the pond with pegs or by trickling dry sand out of a bottle.

If you have already bought the pond liner, make sure at this point that it is big enough to line the pond to your required depth and overlaps the edge by 100-200mm. If you are using a pre-moulded pond liner, use this as a template for marking the pond out. Just remember that if the pond liner is an irregular shape, turning it upside down to mark around it will mean the hole is backwards in relation to the righted lining.

Digging Out the Pond

Start to dig out your pond in the desired shape. Try to have a step in the wall of the pond as this allows for different types of plants and animals. Whatever the depth you plan to have the pond, add 40-50mm to take into account the layer of sand you will need to use.

Once you have the pond the shape and depth you require, carefully check the bottom and edges for sharp stones or roots, etc, which could pierce the pond lining (this is also important if you are using a moulded plastic pond liner).

Fitting the Pond Liner

Before laying the pond liner, you need to lay a 40-50mm layer of soft sand over the bottom and sides of the hole. Dampen the sand to help it form to the sides and press it down firmly to stop it shifting about as much as possible. Now drape the pond liner over the hole and press it carefully down to the bottom.

If you are going to stand in the hole whilst positioning the liner, it can be a good idea to remove your shoes to avoid ripping it. Try not to disturb the layer of sand too much when doing this. It is also a good idea to leave a bit of excess in the bottom of the pond liner to allow it to stretch out under the weight of the water. Weigh down the edge of the liner with blocks or bricks to stop the water pulling it out of shape.

Filling and Trimming the Liner

Slowly fill the pond with a hosepipe, watching to make sure nothing is being pulled out of shape. When the pond is filled to the desired depth, turn off the hose and allow it to settle for a while. The next job is trimming the liner around the edge of the pond. You will need to leave at least 200mm of liner for the overlap. This will allow you to anchor the liner with slabs, etc.

Finishing Off the Pond

If your pond is to be surrounded by paving, etc, make sure you bed down the slabs at the edge of the pond well. You need to try to have the slabs overlap the outer edge of the lining overlap, so that the bed of mortar holds the liner as well as the slab. If the edging slabs are bedded down on the liner without an overlap, the edge will be very unstable. If you want a more natural edge to the pond, you can weigh down the liner overlap with large stones as well as pegging it down with metal or wooden stakes.

A few things to remember about ponds

– If you plan to put fish in your pond, leave it at least four weeks. You can, however, plant up your pond straight away.

– Be careful not to drop mortar into the pond when bedding down the edging slabs. It will contaminate the water.

– Ponds can be dangerous! If you have small children, think about investing in a pond guard.