In the tank: The filter is installed in the tank dome of the underground tank. Due to the internal installation, no additional excavation is required for the filter and no cover is visible in the garden. The easy access to the tank is ensured thanks to the filter which is easy removable.
Outside the tank: The filter is mounted in a shaft housing which is installed in the ground in front of the cistern. External filters are suitable for retrofitting or for drainage of larger roof areas amongst others.
Tip: When installing a tank with a driveable cast iron cover, the use of an external filter with plastic cover may facilitate the maintenance. The filter needs to be installed outside of trafficable areas for this purpose.
suitable for infiltration
The water which is passed into infiltration plants should be filtered first. GRAF recommends the use of basket filters for downstream infiltration systems. Low-maintenance filters always require a wastewater outfall.
Low-maintenance filters are filters with a self-cleaning filter surface and optionally a filter cleaning unit. Pollution from the filter surface will be flushed with the next heavy rainfall in the overflow siphon of the rainwater tank. These filters provide a long-lasting excellent water quality and are especially recommended for the use of rainwater in the house (e.g. washing machine / toilet).
Low-maintenance filters are not suitable for a combination with downstream infiltration systems.
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