Posted by Eric Boullenois - 25 November, 2019
Water is life and ensuring its proper containment has been a priority since a early stage of humanity. Throughout history, wooden, ceramic and stone containers have been used as water reservoirs of natural origin and in some cases man-made, some of which are still of common use. In this article I am going to introduce the variety of forms and types of modern water tanks and the key factors to keep under control to ensure the full efficiency of a water tank.
Shapes and purposes of water tanks
Water tanks serves multiple purposes, they can be used to store water for human consumption, industrial uses, water treatment or even for storage in case of fire. Water tanks can be realized in multiple forms and types, they are often cylindrical due to static reasons but there are also many quadratic basins; they can be buried in the ground, semi-buried or raised. Regardless their use or shape, the material used to build water tanks for several decades has been almost exclusively reinforced concrete, which today is more and more replaced by prestressed concrete to avoid cracks.
What are the factors impacting on the quality of water?
It must be taken into proper account that water is a particularly sensitive resource that can be impacted by a number of negative environmental elements, eg. bacteria, viruses, algae, pH changes and accumulation of minerals and accumulated gases. Contamination can be caused by various factors including piping, tank building materials, mineral and gas intrusion, which is why a properly designed water tank works to specifically address and mitigate all these negative effects. In addition to that a water quality control procedure must also be in place, including a regular cleaning plan on early basis to prevent the growth of algae, bacteria and viruses, especially if in case of a tank containing drinking water.
How to ensure efficiency and durability of your water storage?
There are few key factors to keep under control to ensure the efficiency and durability of the any water storage, here below I listed the most relevant ones:
- Humidity. As the concrete structure of the water tank is always in contact with water, the result is that it remains permanently humid. Combined with oxygen, this is a perfect environment for steel corrosion of the internal steel rebars. This phenomenon is extremely dangerous and must be avoided as it reduces the integrity of the structure, which can then collapse if not treated early enough.
- Deterioration of the surface of the container due to chemical attacks. In some cases the pH of the water can be acid and therefore cause a chemical attack to the concrete surface. In others, it can be soft and because of this damage the concrete. In addition to that, the simple movement of the water in the basin, whether it is natural or caused by pumps, can multiply this phenomenon and have an abrasive effect.
- Cracking of the container. In concrete basins, cracks might usually be caused by hydraulic shrinkage or structural defects. Water can be stored into the reservoir only if the cracks that might occur are bridged by a waterproofing membrane flexible enough to ensure the integrity of the reservoir.
- Water quality. In the specific case of drinking water storages, the water quality is of course of high relevance which is why the design and all materials applied to the surface of the tank itself must fulfill specific requirements which partially vary from Country to Country to ensure the users safety. For a deeper insight regarding the legislation applying to drinking water please refer to the article Varying requirements despite a common legal basis: European legislation regarding synthetic materials in contact with drinking water.
Based on what mentioned above it is clear that while keeping water in a container is a still rather a challenge, protecting and waterproofing carefully the concrete structure is key to ensure the durability of a water storage project. Different waterproofing technologies are today competing on the market, I will explain on the next article the pros and cons of the most common ones.