Surface Tension & Drain Holes

Surface Tension

• Surface tension is the ability or the property of a liquid that allows it to resist forces acting upon it. As it pertains to a drainage system, surface tension refers to water's resistance to the external force of gravity, which pulls the water down through the drain. Georgia State University notes that water molecules on the surface of a body of water adhere more strongly to each other because they do not have other water molecules on all sides of them.

Surfaces

• Drainage systems in homes and buildings are related to the surface tension of the water. Surface tension does not only occur on the outer surface of the water, but also the surfaces where water meets any other boundaries, such as the floor or any walls that it comes into contact with. The tension formed on these surfaces also prevents the water from freely flowing down the drain.

Holes

• The holes through which the water runs as it drains out of an area serve as a surface tension breaker. For each hole that exists, a surface tension breaker exists as well. This creates a greater opportunity for drainage because it gives the forces acting on the water a greater opportunity to break the surface tension. As this occurs, the remaining attractive force of cohesion pulls the remaining water molecules through the drain.

Application

• Understanding surface tension can help you design a drainage system what will allow your roof or basement to drain more quickly. Generally speaking, having multiple drains will be superior to having just one drain. Many small drains will create additional opportunities for water runoff, whereas one large drain hole, although still effective as a drain, will create the breaking of surface tension in only one place. Spreading out your drains over a larger distance will allow the water to flow freely, rather than conglomerate in one spot before going down the drain.