Garden Tiles | Tile Drainage
Earthenware pipes, or ‘tiles’, come in various types and sizes: glazed and porous; large, medium and small.
Porous drainpipes are the best type to use, because water can seep through the sides, which cannot happen with glazed tiles. The sizes of porous pipe usually available from builders merchants are 30 cm (1’) long and have internal diameters of 75 mm (3”), 100 mm (4”), and 150 mm (6”).
Draining a rectangular plot is quite simple if the following method is adopted. First peg out and then excavate a network of trenches (of the depth and spacing suited to thetype, and having the necessary minimum gradient) in a herringbone pattern. Check the levels as work proceeds. The main central drain, containing a 100 mm (4”) diameter pipe, is fed by 75 mm (3”) diameter lateral or side drains.
The pipes should be ‘bedded’, or laid, on a 5 cm (2”) layer of gravel in the bottom of the trench and then covered with gravel to within 45 cm (1-½) of the surface, and finally with topsoil to the surface. Instead of gravel, you can use clinkers or rubble, or, best of all, stones graded from large ones at the bottom, bedding and surrounding the pipes, to small ones at the top. You should start laying from the soakaway or other drainage outlet, and work up the gradient. You should record the position of the pipes, so that you do not disturb them during later cultivation.
An alternative to tile drains is modern perforated plastic pipes, which are cheaper and quicker to lay.