A compact dissolved air flotation facility for treating water or wastewater, said facility characterised by: a water or wastewater collection tank; a flocculation chamber; a dissolved air flotation chamber including a submerged contact chamber for directing water entering the chamber to a surface thereof; a means of pumping, under pressure, water or wastewater out from the water or waste-water collection tank into the submerged contact chamber via the flocculation chamber, water entering the DAF chamber having undergone flocculation including suspended matter; an external pressurised dissolver associated with the DAF chamber, said dissolver adapted to saturate water with air and including an orifice plate assembly at an outlet of the dissolver to create a back pressure in the dissolver; a means of recirculating water out from the DAF chamber and then back into the DAF chamber via said pressurised dissolver, whereby air-saturated water from the dissolver degasses upon entry into the DAF chamber and forms bubbles which adhere to said suspended matter causing it to float to the surface to form a layer of float material; a means of discharging said float material from an upper portion of the DAF chamber in the form of an upper discharge tine such that float material is discharged through said upper discharge line when a water level inside the DAF chamber exceeds that of the upper discharge line; and a chlorination chamber including an inlet which defines the water level in said DAF chamber below the upper discharge line, configured such that treated water from the DAF chamber flows through a lower discharge line of the DAF chamber up to the chlorination chamber inlet; and a valve associated with the lower discharge line and operable between a closed position to prevent flow through said lower discharge line and an open position to allow flow through, said valve adapted to be closed for a predetermined period of time during a treatment cycle to thereby cause said water level in the DAF chamber to rise and for said float material to be discharged through the upper discharge line. a water or wastewater collection tank; a flocculation chamber; a dissolved air flotation chamber including a submerged contact chamber for directing water entering the chamber to a surface thereof; a means of pumping, under pressure, water or wastewater out from the water or waste-water collection tank into the submerged contact chamber via the flocculation chamber, water entering the DAF chamber having undergone flocculation including suspended matter; an external pressurised dissolver associated with the DAF chamber, said dissolver adapted to saturate water with air and including an orifice plate assembly at an outlet of the dissolver to create a back pressure in the dissolver; a means of recirculating water out from the DAF chamber and then back into the DAF chamber via said pressurised dissolver, whereby air-saturated water from the dissolver degasses upon entry into the DAF chamber and forms bubbles which adhere to said suspended matter causing it to float to the surface to form a layer of float material; a means of discharging said float material from an upper portion of the DAF chamber in the form of an upper discharge tine such that float material is discharged through said upper discharge line when a water level inside the DAF chamber exceeds that of the upper discharge line; and a chlorination chamber including an inlet which defines the water level in said DAF chamber below the upper discharge line, configured such that treated water from the DAF chamber flows through a lower discharge line of the DAF chamber up to the chlorination chamber inlet; and a valve associated with the lower discharge line and operable between a closed position to prevent flow through said lower discharge line and an open position to allow flow through, said valve adapted to be closed for a predetermined period of time during a treatment cycle to thereby cause said water level in the DAF chamber to rise and for said float material to be discharged through the upper discharge line.