What does it mean to be “waterproof”? Can anything really be truly waterproof? I’m not speaking philosophically. The question is based on science. The truth is, many things we normally consider to be waterproof actually have a measurable level of permeability. Plastic, glass, even solid steel are all permeable to a small degree. From a purely scientific point of view, it is correct to say that nothing is absolutely waterproof.

The American Concrete Institute agrees. They state that “nothing can be completely ‘impervious’ to water under infinite pressure over infinite time’’ and so they discourage the use of the word “waterproof.” Instead, ACI prefers the word “watertight.” However, ACI then goes on to define watertight as meaning “impermeable to water.” I don’t know about you, but as near as I can tell, impermeable to water and impervious to water mean about the same thing.Remember, this is in context of concrete construction: waterproofing concrete structures like buildings, bridges and tunnels. Or objects cast from concrete-like blocks and pipes. A real-world use of the word as it relates to concrete is simply the prevention of the passage of water through the concrete. In a practical sense this means water does not leak out of a concrete water reservoir or leak into a concrete basement. The permeability of the concrete itself or the materials that you may apply to the concrete is not necessarily relevant. The relevant question is: does water pass from one side of the concrete to the other? If it doesn’t, then it is waterproof concrete by my way of thinking.

One important point to be clarified is that the structure must prevent the passage of water that is under pressure. Stopping water under pressure is the key to the definition because if the water is not under pressure, then what you are doing is simply preventing water absorption.

Water absorption can easily be prevented using water-repellent products or even just a coat of paint. Water under a head of pressure is the situation you find with concrete structures like reservoirs, tunnels and deep basements. Therefore, to achieve a waterproof state, we must prevent the passage of water through the structure when the water is under a head of pressure over a long period of time. This is why real-world waterproofing is always a system. A waterproofing system – for example, a concrete waterproofing system – is an integrated system of measures and products that reliably accomplish this result. Anything else is not waterproofing – it’s wishful thinking.

Can anything truly be waterproof? If by that you mean having a dry basement or leak-free reservoir for the life of that structure, then the answer is yes.