Water quality, hardness and compliance in Hampshire and West Sussex
According to TapWater.uk's analysis, Portsmouth Water scores 8.4/10 for drinking water quality across 2 monitored postcode districts in 2026. The company reports 99.98% compliance with UK drinking water standards.
Scores sorted by lowest first — worst quality at the top.
Reported compliance with UK drinking water standards.
99.98%
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 Portsmouth Water's supply differs from the national picture.
All postcode districts within Portsmouth Water's supply network.
Yes. Across 2 monitored postcode districts, Portsmouth Water's average water quality score is 8.4/10. The lowest-scoring district we monitor is PO4 (8.4/10) and the highest is PO5 (8.4/10).
Hardness readings for Portsmouth Water's districts are still being collected. Enter your postcode on our hardness checker for the reading in your area.
Portsmouth Water reported a 99.98% 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.
Portsmouth Water supplies 0.7 million customers across Hampshire and West Sussex. The postcode districts we monitor in its area: PO4, PO5.
Active incidents affecting Portsmouth 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 Portsmouth Water's own website, which carries the operational updates.