Factories and commercial building generally have large roof surface areas, which makes them ideal to capture and harvest rainwater. The key element to these systems are to make them easy to use and operate and install the correct rainwater harvesting equipment to ensure low system maintenance.
As a company we have installed many small commercial rainwater systems. The typical system as discussed in this article is similar to the system we installed at a factory in Durban. It will consist of one or two 5000l rainwater tanks. Rainwater is harvested using a inline filter connected to the 110mm down-pipes from the gutters. The inline filter is a self-cleaning filter with a 90% to 95% recovery efficiency. This Wisy filter prevents any particle larger that 280 microns from entering the tank. No leafs or large solid material will enter the tank, thus preventing sludge buildup in the rainwater tank and reducing the maintenance significantly. The filter has has no moving part and virtually maintenance free. These types of inline rainwater filters ensure good quality rainwater that remains fresh for longer.
The tank does not require the installation of an overflow because the inline filter stop operating when the tank fills up and simply allows the water to bypasses into the down-pipe.
The clean water in the tank can then be pumped out by our submersible pressure pump to a wash-water or gardening tap where the water can then be used. The system is completely automatic and the pump only switches on when there is a demand for water i.e when the tap or valve is opened. If the tank reaches a low water level the pump will stop operating, protecting it from running dry. When it rains again and the tank fills up, the pump will automatically reset to be used for operation.
The typical cost of these systems range between R14000 and 19000 installed at the factory premises.