Find Your Official Water Quality Checker
Select your water supplier, then use its official checker with your full postcode for current local water-quality and hardness information.
Important: postcode-area estimates are not shown
Filter Authority does not currently present stored postcode-area mappings, typical hardness labels, mg/L figures, supplier-wide averages or lead-risk estimates as verified local data. Water quality and hardness can vary by supply zone and property. This is not a live test or incident-monitoring service.
What is your water source?
Before you start
- Have your full postcode ready; area codes alone are not sufficient.
- Use the supplier named on your water bill where possible.
- Check the result directly with the supplier before choosing water-treatment equipment.
Why the official checker matters
The Drinking Water Inspectorate explains that hardness varies with local geology and advises customers to ask their water company for an accurate measurement. Its published guide sets out the current UK hardness bands.
Read DWI water-hardness guidanceInformation review: official supplier routes were checked on 24 September 2026 and are monitored for availability. This directory is reviewed periodically; information was correct at the time of review, but supplier tools, water sources and technical guidance can change. For current local information, rely on the official checker and your supplier's advice.