Building Concrete Streams: Construction & Flow Design

Constructing a Permanent Concrete Stream

For a more durable stream than pre-formed units or liners, concrete is the answer. It requires more skill than those methods but less than a concrete pool, and is achievable for careful amateurs. Use the same concrete mix as for a pool.

Excavate 10 cm (4 in) larger all round than the finished feature. Line with polythene membrane. Lay all concrete in one day — even a 24-hour gap creates weak points. Keep the final stream design in mind to position rocks for softened edges and flow patterns.

Use a stiff mix to prevent slumping. Apply half the thickness, embed wire mesh reinforcement, then add the final layer. Trowel over contours.

Concrete streams often leave dry soil at the edges. Create planting pockets in the concrete to hold soil kept damp by passing water.

Creating Flow Patterns

Strategic rock placement shapes water movement: a rock barrier with a central gap accelerates flow; varied stones forming a gentle dip create a softer effect; flat stones produce smooth water.

Step-by-Step: Making a Concrete Stream

1. Line stream bed with polythene; add first concrete layer (polythene prevents rapid drying and cracking).
2. Lay reinforcing mesh, add final concrete layer, position edging stones (ideally from same source) for a neat finish.
3. Place stones in the bed to alter flow — depth affects speed reduction, with emergent stones having greatest impact.