A filter for purifying large volumes of water comprising: - a polyester tank having a lower part and an upper part separated by a fixed separating roof and provided of a manhole for the assembly and maintenance of interior components; - a filter cleaning device; - a control panel; - a lower drain with a valve to remove dirt during filter cleaning; - a plurality of flexible tubes secured to and suspended from the fixed separating roof, forming a support for the perlite filtering means; - an upper outlet for filtered water, comprising: - a collector for the inlet and distribution of water to be filtered arranged in the lower part of the tank, with the water outlets facing downwards and connected to a water inlet; - said cleaning device is arranged in the lower part of the tank and comprising a cleaning collector arranged above the collector for the inlet and distribution of water, and consists of a ring of tubes with fixed nozzles and/or movable nozzles facing the upper area of the filter connected to pump means (42, 43) for pumping pressurised fluid into the tank during the cleaning steps thereof; said pump means (42, 43) for pumping pressurised fluid are connected to the control panel and are controlled by it, and comprising: - a blowing pump that introduces pressurised air during regeneration of the perlite and - a water pressure pump that introduces pressurised water during a cleaning step; and an upper opening for the outlet of air provided with air-detecting sensors connected to the control panel and an opening and closing valve for the evacuation of air automatically controlled by the control panel based on the signals provided by the sensors ensuring that the filter remains full of water. - a polyester tank having a lower part and an upper part separated by a fixed separating roof and provided of a manhole for the assembly and maintenance of interior components; - a filter cleaning device; - a control panel; - a lower drain with a valve to remove dirt during filter cleaning; - a plurality of flexible tubes secured to and suspended from the fixed separating roof, forming a support for the perlite filtering means; - an upper outlet for filtered water, comprising: - a collector for the inlet and distribution of water to be filtered arranged in the lower part of the tank, with the water outlets facing downwards and connected to a water inlet; - said cleaning device is arranged in the lower part of the tank and comprising a cleaning collector arranged above the collector for the inlet and distribution of water, and consists of a ring of tubes with fixed nozzles and/or movable nozzles facing the upper area of the filter connected to pump means (42, 43) for pumping pressurised fluid into the tank during the cleaning steps thereof; said pump means (42, 43) for pumping pressurised fluid are connected to the control panel and are controlled by it, and comprising: - a blowing pump that introduces pressurised air during regeneration of the perlite and - a water pressure pump that introduces pressurised water during a cleaning step; - a collector for the inlet and distribution of water to be filtered arranged in the lower part of the tank, with the water outlets facing downwards and connected to a water inlet; - said cleaning device is arranged in the lower part of the tank and comprising a cleaning collector arranged above the collector for the inlet and distribution of water, and consists of a ring of tubes with fixed nozzles and/or movable nozzles facing the upper area of the filter connected to pump means (42, 43) for pumping pressurised fluid into the tank during the cleaning steps thereof; said pump means (42, 43) for pumping pressurised fluid are connected to the control panel and are controlled by it, and comprising: - a blowing pump that introduces pressurised air during regeneration of the perlite and - a water pressure pump that introduces pressurised water during a cleaning step;