How can I protect my water feature against frost?

When water freezes, it expands. This expansion is what causes frost damage. For example, outdoor pipes and taps often split because the water inside the copper pipe freezes. This forces the copper to expand beyond the limit of its flexibility, causing cracking. When the ambient temperature rises and the ice inside melts, the tap or pipe starts to leak. Insulation jackets are often purchased to protect outdoor pipes and taps from freezing.

When a body of standing water freezes

If you left a cup of water outside and the water froze, the cup would almost certainly break. Even if the cup were made of metal, it has the potential to break - this is what happens with the outdoor taps.
Freezing water has the power to crack metal. It all comes down to the flexibility of the material that surrounds the body of water.

Depending on the type of water feature, standing water can occur in various places:

• In an underground reservoir. If the underground reservoir is made of plastic, this will may not be a problem because it will be flexible. However, cracking can still occur in severe frosts.
• In the tubes that transport the water from the reservoir to the top of the feature.
• In any above-ground reservoir. This might be the main reservoir of a self-contained feature, or it might be a small reservoir which has been created for the design appearance. For example the bowls in a terracotta cascade feature. It is advisable to drain a water feature if there is any chance of water inside it freezing.

To surfaces caused by water ingress

Surface damage is dependent on the type of surface. For example, terracotta planters are notorious for frost damage. (Terracotta is often porous, depending on the temperature at which it was fired.) Small amounts of water seep into the surface of the planter. When this water freezes, it cracks the surface, causing small amounts of the terracotta to flake off.
Examine the surface of the feature - if it is even slightly porous, there is a risk of surface damage caused by frost.
If there is a chance of surface damage, the feature should be brought inside or inside a garage, or covered to reduce the chances of freezing.

Pumps can be damaged if they are left in a body of water that freezes, or if water is left inside the pump which then consequently freezes.

To be confident, it is advisable to drain a water feature if there is any chance of water inside it freezing.
If there is a chance of surface damage, the feature should be brought inside or inside a garage, or covered to reduce the chances of freezing.