Water quality: nitrates directive
The EC Nitrates Directive has set the safe limit for nitrates in surface and ground waters as 50 mg/l. Surface and ground waters in England and Wales are monitored and nitrate levels recorded. Where nitrates are found to be consistently above the set limit and this is attributed to agriculture, an action programme is required to reduce these levels.
Approximately 70% of agricultural land in England is designated as a Nitrate Vulnerable Zone (NVZ).
The action programme has to be revised every four years. Therefore the rules change frequently. Details on the current rules can be found here.