Rainwater harvesting



Money doesn’t grow on trees but water does fall from the sky.



2nd class water


Much of the water used by an enterprise does not need to be 1st class potable (drinking) water. Do you really need potable water to flush toilets with, irrigate plants, use in scrubbers, chillers, or wash vehicles with?


Rainwater is an excellent source of water for many of these applications. An added advantage to using rainwater is that it is very soft with no dissolved chlorides or calcium – this makes it ideal for use in industrial reverse osmosis or water cooled chiller applications.


It is worth examining your enterprises operations to identify the quantity of water which does not need to be of potable standards. Once you know the demand for 2nd class water, you can identify whether it can be met by rainwater.


Annual supply = roof area * 0.55 (for Malta)


How can you harvest rainwater?


All you need is a collection area, storage, treatment, and a means of distributing the rainwater to your preferred application.


The collection area is normally a roof, the storage area is traditionally an underground cistern. These cisterns however can be expensive to construct and waterproof, particularly on premises where they need to be retrofitted. Luckily there are nowadays cheaper alternatives on the market. These include above ground tanks, and modular underground tanks.


Treatment can be as simple as a screen to filter particles out of the rainwater, to a reverse osmosis and UV-purification system to treat the water up to 1st class (potable) standards. It depends on your individual requirements and engaging an expert consultant is recommended. Distribution involves pumping the treated rainwater to its intended use.


Costs involved in harvesting rainwater


Harvested rainwater is the cheapest source of water, estimated at costing as little as 10 cents per m3. Costs for the equipment vary significantly, from a few hundred euros to several thousand, depending on the set up required and the infrastructure already in place.


Online Self-Assessment Tool – is rainwater harvesting for you?


Our online self-assessment tool can evaluate the potential for rainwater harvesting in your premises. The tool assumes that you will use rainwater only for the flushing of toilets, however a more in-depth study could reveal other uses of rainwater. If you would like an indication of other uses book a water audit here.



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