The Preformed Basin
If you want a water source in your garden, the most practical thing to do is to install a preformed basin. These exist in all shapes and sizes, and come with or without a cascade or a fountain, depending on whether you want a natural basin or a more sophisticated one.
These basins are generally made of polyehthylene, but also come in synthetic resin or polyester. Their capacity depends very much on their shape.
Standard models range from a capacity of 60 litres to over 800 litres.
There is a wide variety of shapes. Some have strictly geometric shapes like squares, circles, ovals or rectangles, while others have more natural shapes with preformed levels varying in depth.
Unlike a tarpaulin system, the advantage of this type of basin is that it is naturally leakproof the moment it is installed. The rigidity of the material means there is no risk of the banks on the sides falling in, even if it is a deep basin. It is easy to install, but certain precautions should be taken in order to ensure its longevity.
The first step is to place the basin on the ground where you want to install it and mark the space it will take up with pickets, for example. The earth should be dug around the basin leaving a wide margin on the sides. A margin if 15 cms. is usually used. A margin of 3 to 5 cms. is used for the depth. The basin is then placed in the hole dug out for it to make sure that it is big enough. When you are happy with the size of the hole, lay down 3 or 4 cms. of clay at the bottom of the hole to ensure the stability of the basin. Make sure to press it down well and verify that the surface is perfectly flat. It is recommended to use a spirit level to ensure that the upper edge is exactly where you want it. Put the basin into position once you have done this.
Another verification with the spirit level should be carried out. Start banking up the soil to a height of around 20 cms., and then fill it up with water to the same level. Alternate banking up and filling with water, 20 cms. at a time. Pack the banking soil down well and water it so as to hold the basin firmly in place. You can install your plants at the same time. Wait for around a month before putting fish into the basin, as the vegetation needs time to acclimatize.