In a nutshell
In this activity we will be informed about the various tanks and systems that are used for rainwater harvesting; and how such systems are constructed.
Rainwater Harvesting Systems in practice
Water-readings
The rainwater harvesting tanks
As we see in the Rainwater harvesting Section a rainwater collecting system has as main operating features the catchment surface, the pipes and pumps, the collection tank, ans some kind of filters (to clean the water). The tanks to store rainwater () vary in terms of size and materials used. In any case, their size should be proportional to the size of the collection surface. Apart from the amount of water to be collected and stored, another criteria to choose the tank is the available budget. The most commonly used rainwater harvesting tanks are made of concrete, plastic and metal.
Play & learn
Let’s find out what are the “advantages” and “disadvantages” of the different material used in tanks for rainwater harvesting.
Move the mouse over the pictures to get all details!
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Water-readings
Open water reservoirs
Open water reservoirs are barriers that impound rainwater, stormwater and stream runoff. The open water reservoirs are constructed to collect water for supply and irrigation, mainly in rural communities.
One can say that the open water reservoirs have as strong points that they collect large water volume; they have a long lifespan; and, they can prevent floods. Nevertheless, in their “weak” points we may say the water losses from evaporation; the stagnant water; the difficulties they have in their maintenance or repairing.
Watch this video about a large scale (municipal) rainwater harvesting system installed in Sikinos Island, Greece by the NCWR in the Mediterranean Programme.
Open rainwater harvesting reservoir installed in Nisyros Island, Greece
Water-readings
The modular RWH system
Another type of tanks is the “modular underground” one. The tank comprises of three-dimensional fittings of cubic form units that have a 95% capacity because of the lightweight skeletal structure of each unit. The units are made of recycled polypropylene, a high resistance and sustainable material.
How are these structures installed?
First, the site is excavated and the base is prepared, to be covered with a layer of thin sand to a depth of 100 mm. A non-woven and/or a is installed on the base. The modules are assembled to the desired configuration and then, placed in the base. Piping is installed and then the geotextile and/or the geomembrane are wrapped around the installed modules. Clean sand backfill is placed around the sides and above the tank. The subsurface nature of the modular tanks frees up space for surface landscaping, driveway or parking lot use while meeting the storm water detention requirements of an area.
Preparation of the base
Installation of the modular tank
The structure before closing up the surface
Watch this video showing the installation process.