The National Underground Asset Register (NUAR) is a government digital service operated by Ordnance Survey. It provides authorised users with secure, instant access to a standardised map of underground pipes and cables across England, Wales and Northern Ireland. By bringing asset information together in one view, NUAR helps simplify the process of finding and comparing data that was previously held by multiple organisations in varied formats and scales.

The service is designed for asset owners in telecommunications, energy, pipelines, water, transport and local government, as well as contractors working directly on their behalf to install, maintain, operate or repair buried infrastructure. Its maps support safer excavation, better planning and operational efficiency by helping users identify underground assets before work begins and reducing the time spent requesting information.

NUAR currently publishes data from more than 390 asset owners, covering over 3.2 million kilometres of pipes and cables, or around 80% of known underground assets.