How to construct a simple Garden Pond

Tools

• Spade or shovel
• Concrete mixer, or wheel barrow for smaller ponds
• Garden hose with spray nozzle
• Bucket and hose water level or carpenters level

Materials

• Heavy gauge polythene sheet (enough to line your size pond and extend at least 150mm (6″) beyond the perimeter of the pond comfortably).
• Gravel/sand mix and cement. A pond of 5 square metres (6 sq yards) will need .3 cubic metres (.4 cubic yards) of gravel/sand mix and about one and a half 40 kg (80 lb) bags of cement.
• An array of flat stones (enough to go neatly around the edge of the pond).
• A can of spray paint for marking pond perimeter.

Instructions

Step 1

• Mark out your desired shape of the pond with a can of spray paint.

A Helpful Note from Ted about Extreme Conditions:
“For those of us in the Great White North [Canada], where temperatures vary greatly, the pond – especially if being used for fish and plants should be at a depth of 900mm with a shelf area for some species of plants at approximately 300mm from the top. Although in Canada, this will not stop the pond from becoming a large ice cube, it will prevent broiled fish in the summer from excessive heat. Again, in northern climes, one would have to add wire mesh to keep the pond together. A far better solution would be to use the heavy rubberized liners that are available for fish ponds, eliminating the need for cement. As for the pump – if you are adding one for aeration or a decorative waterfall, that will do the trick”.
Ted L   Stratford, PE

Another Note:
In some places, pools deeper than 400mm (16″) need to be fenced and need a permit. Check with your local Authority.

Step 2

• Check the ground height along your marked line about every 600mm (2ft). You want these points level with each other. You can do this by using our bucket and hose water level method. For instructions on how to make and use a bucket and hose water level click here

Step 3

• Using a spade level out the marked line, following around the perimeter of the pond. Dig about 200mm (8″) wide and 50mm (2″) below existing ground level at the lowest point.

• This is now the shelf around the perimeter of the pond and is where the flat stones will be placed once the concrete has been poured.

Step 4

• Dig the pond out from the pond shelf, sloping gradually down to the centre (saucer shaped) to a maximum depth of 400mm (16″).
• Lay the polythene on the bottom of the pond and up over the pond shelf leaving at least 150mm (6″) spill past the pond edge.

Step 5

• Lay the flat stones temporarily around the shelf of the pond to ensure they fit in place and that you have enough. Remove them out of the way about 400mm (16″) from the shelf edge, until the concrete is poured.

Step 6

• CONCRETE  In a concrete mixer, (or wheel barrow for small pond) mix four parts fine gravel and sand mix, to one part of cement. Pour enough clean water to the mix, to make a fairly stiff mixture. If the mixture is too dry add more water. If the mixture it too wet, add more gravel/sand mix and cement to the same ratio as above.
• Spread the concrete over the entire polythene liner starting at the bottom of the pond, and finishing up at the pond shelf. The concrete should be at least 50mm (2″) thick. Use a block of wood for a trowel, as the edges on a conventional trowel are too sharp and likely to pierce the polythene liner.

Step 7

• Lay the flat stones around the edge of the pond shelf, pushing them slightly into the concrete.
• A large overhanging flat stone, strategically placed, can provide shade for fish, but be sure it is fixed firmly in place, and capable of taking any weight which might be placed on it later.

Step 8

• After a couple of hours (more or less depending on the weather or temperature) the concrete should be stiff enough to allow the pond to be filled with water.
  When filling, place an old sheet, piece of polythene or similar in the pond, so the flow of water does not scour the concrete.
• After filling remove the sheet, and leave the pond to set for about a week. After the week is up, empty and refill the pond three or four times to reduce alkaline level.

You can empty your pond by either

a – a bucket for a small pond,
b – hire a pump from any hire centre,
c – siphoning using the garden hose.

To siphon

• Connect one end of your hose to the garden tap and place the other end at the bottom of the pond. Use a rock or weight of some sort to keep it submerged.
• Turn on the tap to enable the hose to fill up with water. Once the hose is full of water and has started to run into the pond, turn off the tap.
• Unclip the hose from the tap and put your thumb on the end of the hose so no water can escape and no air can get in.
• Carry that end of the hose to an area lower than the bottom of the pool.
• Take your thumb off the hose and the pool will start siphoning. The lower the area is below the pool, the faster the pool will siphon.