Tap water quality in Southampton
Southampton has hard water (297 mg/L CaCO₃), supplied and treated to UK drinking water standards.
Supplied by Southern Water · Southern Water E01032748 · Based on DWI laboratory analysis
Nitrates
34.75mg/L
Chlorine
0.63mg/L
Lead
0.06µg/L
Water hardness
297 mg/L CaCO₃
Hard
Your area has hard water. This can affect skin conditions and cause limescale buildup.
Parents: nitrate levels are elevated
Consider a filter rated for nitrates when preparing infant formula, and follow NHS guidance on boiling water.
How readings compare to limits
Nitrates
34.75 mg/L
PCV / limit: 50 mg/L
Chlorine
0.63 mg/L
No UK limit · WHO guideline 5 mg/L
Lead
0.06 µg/L
PCV / limit: 10 µg/L
Hardness (as CaCO₃)
297 mg/L CaCO₃
Hard
What these readings mean
UK drinking water is regulated under the Water Supply (Water Quality) Regulations 2016, which set a prescribed concentration value (PCV) for each substance. Southern Water must sample against these and report the results to the Drinking Water Inspectorate.
Nitrates in Southampton
34.75 mg/L·UK limit 50 mg/L
Nitrates come mainly from agricultural fertiliser and sewage reaching groundwater. Healthy adults process them without difficulty; the limit exists principally to protect bottle-fed infants under six months.
Lead in Southampton
0.06 µg/L·UK limit 10 µg/L
Water leaves the treatment works lead-free. Any lead is picked up from the pipework between the main and your tap, so the reading depends heavily on your own property — pre-1970 homes are the ones worth checking.
Chlorine in Southampton
0.63 mg/L·UK limit no statutory limit
Added as a disinfectant and required to remain present through the network to keep water safe in transit. Typically 0.2–0.5 mg/L at the tap. A noticeable taste is usually harmless and fades if water stands in a covered jug.
Living with hard water in Southampton
At 297 mg/L CaCO₃, Southampton sits firmly in the hard water band. Hardness is dissolved calcium and magnesium picked up as water passes through chalk and limestone. It is not a health risk — the minerals are the same ones found in food — but it has practical consequences.
- Limescale. Kettles, showerheads and heating elements scale up faster. Descaling every few months keeps appliances efficient.
- Skin. Some people with eczema find hard water aggravates symptoms, though the evidence on softeners as a treatment is mixed rather than settled.
- Soap and detergent. Hard water needs more of both to lather, which is why dishwasher salt exists.
Common questions about Southampton tap water
Is Southampton tap water safe to drink?
Southampton tap water is supplied by Southern Water and is treated to UK drinking water standards. Our latest figures show nitrates at 34.75 mg/L, lead at 0.06 µg/L and chlorine at 0.63 mg/L, with nitrates elevated enough to be worth noting if you are preparing infant formula. Readings vary by supply zone, so check your exact postcode.
Is Southampton hard or soft water?
Southampton has hard water. Lab results put hardness at 297 mg/L CaCO₃, which is classed as hard on the UK scale.
What is the water hardness in Southampton?
Water hardness in Southampton is hard (297 mg/L CaCO₃). Above roughly 200 mg/L you can expect limescale in kettles and appliances, and some people find hard water aggravates dry skin.
Who supplies the tap water in Southampton?
Tap water in Southampton is supplied by Southern Water. They are responsible for treatment, distribution and the laboratory testing reported to the Drinking Water Inspectorate.
Sewage spills in Southampton
Official Environment Agency storm overflow data near the town centre.
Check your postcode
Look up any UK address for lab results and nearby overflows.