Northumbrian Water Limited is a water company in the United Kingdom, providing mains water and sewerage services in the English counties of Northumberland, Tyne and Wear, Durham and parts of North Yorkshire. Northumbrian Water Limited also supplies water in eastern England under the name Essex and Suffolk Water. It is a wholly owned subsidiary of Northumbrian Water Group.

Northumbrian Water Limited is a private limited company registered in England and Wales under company number 2366703, incorporated in this form in 1989.

The Northumbrian Water Authority (NWA) was a regional water authority created under the Water Act 1973. It became Northumbrian Water Limited when privatised in 1989.

The water authority was formed by taking over the existing public water supply infrastructure in the area:

Three private statutory water companies operated within its area:

The Newcastle and Gateshead Water Company merged with the Sunderland and South Shields Water Company in 1994 to form North East Water, which itself became part of Northumbrian Water in 1995.

The Darlington Gas and Water Company's undertakings acquired by Darlington Local Board of Heath under the Darlington Local Board Act 1854 (17 & 18 Vict. c. clxxxi), becoming Darlington Corporation Water Department when Darlington became a municipal borough in 1867.

The Darlington Gas and Water Company was created by the Darlington Gas and Waterworks Act 1849 (12 & 13 Vict. c. viii).