<p>An oil from water separation system (20) including an oil disengagement chamber (21) in communicatiion with an effluent water chamber (85) from which a volume of effluent water equal to an oil and water accumulation volume (29) is controllably discharged by way of a flow retarding device (26) wherein rate of outflow is a function of the head of the liquid in the effluent water chamber (85). The flow retarding device can take the form of a siphon pipe (22) or one or more bleed apertures (33, 43).</p>
