Patent ID: 7252761

Claim:
A filtration installation for filtering water of a water pool ( 2 ), in particular of a swimming pool, arranged to be filled with water up to a predetermined water level ( 3 ), which installation comprises a filter vessel ( 4 ) separate from the water pool ( 2 ) and containing a filter bed ( 5 ), the filter vessel ( 4 ) being arranged to be installed next to the pool ( 2 ) with its filter bed ( 5 ) situated at least partially underneath said predetermined water level ( 3 ), with at least one inlet pipe ( 6 ) extending between the pool ( 2 ) and an upper portion ( 12 ) of the filter vessel ( 4 ) for conducting water from the pool ( 2 ) to the filter vessel ( 4 ) and with at least one return pipe ( 8 ) extending between a lower portion of the filter vessel ( 4 ) and the pool ( 2 ) for conducting filtered water having passed through the filter bed ( 5 ) to the pool ( 2 ), the installation further comprising a reversible pump ( 9 ) enabling to generate, in a backwashing state, an upward flow of water through the filter bed ( 5 ), and at least one drain pipe ( 11 ) arranged for removing the water pumped by the pump ( 9 ) in its backwashing state through the filter bed ( 5 ) into the upper portion ( 12 ) of the filter vessel ( 4 ), characterised in that the upper portion ( 12 ) of the filter vessel ( 4 ) is in liquid communication through said inlet pipe ( 6 ) with the water in the pool ( 2 ) so that water from the pool ( 2 ) can flow by gravity through the inlet pipe ( 6 ) into the filter vessel ( 4 ), the inlet pipe ( 6 ) is provided with a one-way valve ( 10 ) arranged to prevent a flow of water from the upper portion ( 12 ) of the filter vessel ( 4 ) into the pool ( 2 ), the drain pipe ( 11 ) is arranged upstream the filter bed ( 5 ) but downstream the one-way valve ( 10 ), and said reversible pump ( 9 ) is disposed downstream the drain pipe ( 11 ) so that the water pumped upwards through the filter bed ( 5 ) in the backwashing state of the pump ( 9 ) is removed through the drain pipe ( 11 ) whilst in the reversed filtering state of the pump ( 9 ), water is pumped out of the pool ( 2 ) to generate a flow of water from the pool ( 2 ) through the inlet pipe ( 6 ), the filter bed ( 5 ) and the return pipe ( 8 ) back to the pool ( 2 ).