Blackwater is a village in Cornwall, England.
It is situated within the TR4 postcode district, which is within the Truro post town.
The full list of postcode districts within the Truro post town is as follows:
The Truro post town is within the Truro postcode area.
Administrative Ward: St Agnes
Administrative District: Cornwall
Country: England
UK Parliament: Truro and Falmouth
NHS Local Health Authority: South West
NHS Region: Southern