More than 8,000 litres of spilt milk were washed down drains after a tanker overturned.
Another 16,000 litres were saved and pumped into a second tanker after the accident at Titnore Lane, Clapham, close to the junction with the A27, near Worthing.
Southern Water was alerted because of concerns large quantities of milk could end up polluting rivers.
Sand bags were used to contain the spillage while firefighters trained hoses on to the milk to dilute it.
The driver of the tanker suffered minor injuries and was taken to Worthing Hospital.
The road was closed for five hours yesterday morning and there were long tailbacks on the A27.
Police alerted schools so parents could make alternative arrangements to pick up their children.
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