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tapwater
England and Wales average 9.0

Tap water in SG7, North HertfordshireSafe to drink.Very hard.

Supplied by Affinity Water. 445 samples, 24 substances, latest on 10 December 2025. Everything is inside the legal limit, and nothing comes close to it.

Get softener quotes for SG7See everything that was tested

9.3 / 10

The tank is as full as the score. The specks are the minerals that make water hard.

What to do about it

Hard water: compare softener quotes

At 323 mg/L a softener is the only thing that stops limescale. Filters do not soften water.

It pays for itself in most homes at this hardness, through a boiler that stays efficient and appliances that last.

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What's in a glass of SG7 water

Every bubble is a substance the lab measured. The higher it floats, the closer it came to its legal limit, the dashed line at the top.

Nitrate came closest to a limit, at 68% of it. 20 of 21 substances used under a quarter of theirs.

0%25%50%75%limitLegal limitAntimony: 0.000027 mg/L, <1% of the 0.005 mg/L limitAntimony<1%Manganese: 0.000363 mg/L, <1% of the 0.05 mg/L limitManganese<1%Chromium: 0.000383 mg/L, <1% of the 0.05 mg/L limitChromium<1%Selenium: 0.000352 mg/L, <1% of the 0.04 mg/L limitSelenium<1%Aluminium: 0.00199 mg/L, <1% of the 0.2 mg/L limitAluminium<1%Cadmium: 0.000054 mg/L, 1% of the 0.005 mg/L limitCadmium1%Copper: 0.036 mg/L, 2% of the 2 mg/L limitCopper2%Nitrite: 0.01 mg/L, 2% of the 0.5 mg/L limitNitrite2%Mercury: 0.000023 mg/L, 2% of the 0.001 mg/L limitMercury2%Turbidity: 0.11 NTU, 3% of the 4 NTU limitTurbidity3%Arsenic: 0.000279 mg/L, 3% of the 0.01 mg/L limitArsenic3%Iron: 0.00897 mg/L, 4% of the 0.2 mg/L limitIron4%Boron: 0.046 mg/L, 5% of the 1 mg/L limitBoron5%Nickel: 0.000988 mg/L, 5% of the 0.02 mg/L limitNickel5%Trihalomethanes: 0.00812 mg/L, 8% of the 0.1 mg/L limitTrihalomethanes8%Fluoride: 0.137 mg/L, 9% of the 1.5 mg/L limitFluoride9%Colour: 2 mg/L Pt/Co, 10% of the 20 mg/L Pt/Co limitColour10%Lead: 0.00117 mg/L, 12% of the 0.01 mg/L limitLead12%Ammonia: 0.06 mg/L, 12% of the 0.5 mg/L limitAmmonia12%Bromate: 0.00147 mg/L, 15% of the 0.01 mg/L limitBromate15%Nitrate: 34.1 mg/L, 68% of the 50 mg/L limitNitrate68%
  1. Nitrate68%
  2. Bromate15%
  3. Ammonia12%
  4. Lead12%
  5. Colour10%
  6. Fluoride9%
  7. Trihalomethanes8%
  8. Nickel5%
  9. Boron5%
  10. Iron4%
  11. Arsenic3%
  12. Turbidity3%
  13. Mercury2%
  14. Nitrite2%
  15. Copper2%
  16. Cadmium1%
  17. Aluminium<1%
  18. Selenium<1%
  19. Chromium<1%
  20. Manganese<1%
  21. Antimony<1%
  • E. coli none found
  • Coliform Bacteria none found
  • Conductivity 668 µS/cm
All 24 results as a table
SubstanceResultLegal limitShare of limit
Boron0.046 mg/L1 mg/L
5%
E. coli0 count/100mlMust be zeroNone found
Copper0.036 mg/L2 mg/L
2%
Colour2 mg/L Pt/Co20 mg/L Pt/Co
10%
Coliform Bacteria0 count/100mlMust be zeroNone found
Antimony0.000027 mg/L0.005 mg/L
<1%
Chromium0.000383 mg/L0.05 mg/L
<1%
Fluoride0.137 mg/L1.5 mg/L
9%
Conductivity668 µS/cmNo legal limit–
Turbidity0.11 NTU4 NTU
3%
Ammonia0.06 mg/L0.5 mg/L
12%
Iron0.00897 mg/L0.2 mg/L
4%
Trihalomethanes0.00812 mg/L0.1 mg/L
8%
Aluminium0.00199 mg/L0.2 mg/L
<1%
Nitrite0.01 mg/L0.5 mg/L
2%
Manganese0.000363 mg/L0.05 mg/L
<1%
Nickel0.000988 mg/L0.02 mg/L
5%
Bromate0.00147 mg/L0.01 mg/L
15%
Selenium0.000352 mg/L0.04 mg/L
<1%
Cadmium0.000054 mg/L0.005 mg/L
1%
Lead0.00117 mg/L0.01 mg/L
12%
Arsenic0.000279 mg/L0.01 mg/L
3%
Mercury0.000023 mg/L0.001 mg/L
2%
Nitrate34.1 mg/L50 mg/L
68%

323mg of limescale minerals in every litre

This is the water that furs up kettles

Very hard on the UK scale. It is fine to drink. It is hard on boilers, showers, skin and anything that heats water, and a jug or tap filter will not change that.

Soft400 mg/L

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Outside your tap

Your river is the Ivel (US Henlow), rated good

The Environment Agency rated the Ivel (US Henlow) as good for ecological health in its 2025 assessment, meaning the river is only slightly changed from its natural state. It fails the chemical test, as every river, estuary and stretch of coast in England does, because of long-lasting pollutants such as mercury, PFOS (a forever chemical) and old flame retardants.

None of this is a test of your tap water. Environment Agency record · River health across England

SG7 in short

Tap water in SG7 (North Hertfordshire) is supplied by Affinity Water in the North Hertfordshire Central zone and scores 9.3 out of 10, against an England and Wales average of 9.0. None of the 24 tested substances came close to a limit. The latest sample is from 10 December 2025.

  • Among the hardest water in the country at 323 mg/LVery hard starts at 250 mg/L. At this level kettles scale up within weeks and a softener is a normal purchase in SG7. How hardness is measured
  • Nitrate is the reading closest to its limit, at 68% of the 50 mg/L maximumIt passed with room to spare, and everything else tested sat further below its limit. See every reading
  • 2nd cleanest of 6 areas tested in North HertfordshireOnly 1 area in North Hertfordshire scored higher. The best is SG6 on 9.3.

Next door

SG39.1 out of 10 · 296 mg/LSG69.3 out of 10 · 294 mg/LSG58.9 out of 10 · 368 mg/LSG88.8 out of 10 · 273 mg/LSG48.9 out of 10 · 368 mg/L

Questions about SG7 water

Is SG7 tap water safe to drink?

Based on the latest tests, SG7 (North Hertfordshire) water scores 9.3/10, which is safe. 0 of 24 tested contaminants exceeded recommended levels. Water is supplied by Affinity Water.

What contaminants are in SG7 water?

We tested 24 contaminants in SG7 water. None exceeded recommended safe levels.

Who supplies water in SG7?

SG7 (North Hertfordshire) is supplied by Affinity Water. You can view their full profile and compliance data on our supplier page.

Is SG7 water hard or soft?

Water in SG7 (North Hertfordshire) has a hardness of 323 mg/L CaCO3, which is classified as very hard. Hard water can cause limescale buildup. A water softener or filter jug may help.

Should I use a water filter in SG7?

SG7 water scored 9.3/10 with no contaminants above recommended levels. A filter is optional but can improve taste, especially if you notice a chlorine flavour. See our filter recommendations for your area.

Are there PFAS forever chemicals in SG7 water?

No PFAS (forever chemicals) result is attached to the tap-water tests for SG7, and the Environment Agency has no PFAS detections in rivers or groundwater within 10 km of it. That reflects where sampling has happened as much as the water itself.

How clean is the river near SG7?

The Environment Agency rated the Ivel (US Henlow) as good for ecological health in its 2025 assessment, meaning the river is only slightly changed from its natural state. It fails the chemical test, as every river, estuary and stretch of coast in England does, because of long-lasting pollutants such as mercury, PFOS (a forever chemical) and old flame retardants. This is a rating of the river, not of tap water in SG7, which is treated before it reaches homes.

Keep reading

How to test your waterBest water filtersFilter shower headsWater testing kitsUK water rankingsWater hardness checkerWater hardness map

River and groundwater readings near SG7

Environment Agency samples from rivers, groundwater and reservoirs nearby. Not your tap water. For scale they are shown against drinking water limits; rivers are judged against much stricter environmental standards, and on those every river in England fails for chemicals.

SubstanceReadingDrinking water limit
Iron0.33 mg/L0.2 mg/L
pH7.54 pHNone
Temperature10.9 °CNone
Conductivity704 µS/cmNone
Nitrate12 mg/L50 mg/L
Nitrite0.023 mg/L0.5 mg/L
Phosphate0.048 mg/LNone
Dissolved Oxygen9.17 mg/LNone
Lead0.00011 mg/L0.01 mg/L
Zinc0.011 mg/LNone
Nickel0.0088 mg/L0.02 mg/L
Manganese0.011 mg/L0.05 mg/L
Copper0.00018 mg/L2 mg/L
Aluminium0.022 mg/L0.2 mg/L

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Source: Affinity Water test results, published through the Stream Water Data Portal; rivers and PFAS from the Environment Agency. Page updated . How we score · Where the data comes from