Water quality, hardness and compliance in Devon and Cornwall
According to TapWater.uk's analysis, South West Water scores 9.5/10 for drinking water quality across 4 monitored postcode districts in 2026. The company reports 99.92% compliance with UK drinking water standards, and the average hardness across its monitored districts is 45 mg/L CaCO₃.
Scores sorted by lowest first — worst quality at the top.
Measured per district; 0% of monitored districts read hard or very hard, averaging 45 mg/L CaCO₃.
Hard water is safe to drink but drives limescale in kettles, boilers, and appliances. Check your exact postcode or read our water softener guide if scale is a daily battle in your home.
Reported compliance with UK drinking water standards.
99.92%
Compliance above 99.9% is the norm across the UK industry, which is why a compliance figure alone says little about how your water actually tastes, scales, or reads locally. The per-district scores and flagged contaminants above are where South West Water's supply differs from the national picture.
All postcode districts within South West Water's supply network.
Yes. Across 4 monitored postcode districts, South West Water's average water quality score is 9.5/10. The lowest-scoring district we monitor is EX1 (9.4/10) and the highest is PL2 (9.5/10).
Across 4 monitored districts in South West Water's area, the average hardness is 45 mg/L CaCO₃ and 0% of districts read hard or very hard. Limescale pressure is moderate to low for most of this supply area.
South West Water reported a 99.92% compliance rate against UK drinking water standards. Compliance above 99.9% is the industry norm, which is exactly why we also publish per-district environmental scores and flagged contaminant counts: legal compliance and local water character are different questions.
South West Water supplies 1.8 million customers across Devon and Cornwall. The postcode districts we monitor in its area: EX1, EX2, PL1, PL2.
Active incidents affecting South West Water appear at the top of this page as soon as our monitoring picks them up, alongside the affected postcodes. For supply emergencies always check South West Water's own website, which carries the operational updates.