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tapwater
England and Wales average 9.0

Tap water in SG1, StevenageNitrite is over the limit.Very hard.

Supplied by Affinity Water. 506 samples, 24 substances, latest on 16 December 2025. Nitrite came in above the legal limit. Everything else passed.

Get softener quotes for SG1See everything that was tested

8.9 / 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 321 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 SG1 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.

Nitrite is over its legal limit, at 125% of it.

0%25%50%75%limitLegal limitCopper: 0.014 mg/L, <1% of the 2 mg/L limitCopper<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%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%Antimony: 0.000061 mg/L, 1% of the 0.005 mg/L limitAntimony1%Selenium: 0.000585 mg/L, 1% of the 0.04 mg/L limitSelenium1%Mercury: 0.000023 mg/L, 2% of the 0.001 mg/L limitMercury2%Trihalomethanes: 0.00257 mg/L, 3% of the 0.1 mg/L limitTrihalomethanes3%Arsenic: 0.000312 mg/L, 3% of the 0.01 mg/L limitArsenic3%Turbidity: 0.15 NTU, 4% of the 4 NTU limitTurbidity4%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: 0.00115 mg/L, 6% of the 0.02 mg/L limitNickel6%Lead: 0.000673 mg/L, 7% of the 0.01 mg/L limitLead7%Colour: 2 mg/L Pt/Co, 10% of the 20 mg/L Pt/Co limitColour10%Fluoride: 0.164 mg/L, 11% of the 1.5 mg/L limitFluoride11%Ammonia: 0.06 mg/L, 12% of the 0.5 mg/L limitAmmonia12%Bromate: 0.0015 mg/L, 15% of the 0.01 mg/L limitBromate15%Nitrate: 31.2 mg/L, 62% of the 50 mg/L limitNitrate62%Nitrite: 0.624 mg/L, 125% of the 0.5 mg/L limitNitrite125%
  1. Nitrite125%
  2. Nitrate62%
  3. Bromate15%
  4. Ammonia12%
  5. Fluoride11%
  6. Colour10%
  7. Lead7%
  8. Nickel6%
  9. Boron5%
  10. Iron4%
  11. Turbidity4%
  12. Arsenic3%
  13. Trihalomethanes3%
  14. Mercury2%
  15. Selenium1%
  16. Antimony1%
  17. Cadmium1%
  18. Aluminium<1%
  19. Chromium<1%
  20. Manganese<1%
  21. Copper<1%
  • E. coli none found
  • Conductivity 570 µS/cm
  • Coliform Bacteria none found
All 24 results as a table
SubstanceResultLegal limitShare of limit
Nitrite0.624 mg/L0.5 mg/L
125%
E. coli0 count/100mlMust be zeroNone found
Conductivity570 µS/cmNo legal limit–
Coliform Bacteria0 count/100mlMust be zeroNone found
Colour2 mg/L Pt/Co20 mg/L Pt/Co
10%
Manganese0.000363 mg/L0.05 mg/L
<1%
Chromium0.000383 mg/L0.05 mg/L
<1%
Turbidity0.15 NTU4 NTU
4%
Lead0.000673 mg/L0.01 mg/L
7%
Aluminium0.00199 mg/L0.2 mg/L
<1%
Copper0.014 mg/L2 mg/L
<1%
Nitrate31.2 mg/L50 mg/L
62%
Cadmium0.000054 mg/L0.005 mg/L
1%
Fluoride0.164 mg/L1.5 mg/L
11%
Mercury0.000023 mg/L0.001 mg/L
2%
Ammonia0.06 mg/L0.5 mg/L
12%
Nickel0.00115 mg/L0.02 mg/L
6%
Selenium0.000585 mg/L0.04 mg/L
1%
Arsenic0.000312 mg/L0.01 mg/L
3%
Bromate0.0015 mg/L0.01 mg/L
15%
Iron0.00897 mg/L0.2 mg/L
4%
Antimony0.000061 mg/L0.005 mg/L
1%
Boron0.046 mg/L1 mg/L
5%
Trihalomethanes0.00257 mg/L0.1 mg/L
3%

321mg 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 Stevenage Brook, rated poor

The Environment Agency rated the Stevenage Brook as poor for ecological health in its 2025 assessment, meaning the river is badly affected, with much of the expected wildlife missing. It is held back by fish, water plants and algae and insects and other small river life. 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

SG1 in short

Tap water in SG1 (Stevenage) is supplied by Affinity Water in the Stevenage Central zone and scores 8.9 out of 10, against an England and Wales average of 9.0. 1 of 24 tested substances was close to or over a limit. The latest sample is from 16 December 2025.

  • Nitrite was measured at 0.62 mg/L, 25% over the UK limitIt is the only one of 24 tested substances to go over its limit. See the full results
  • Among the hardest water in the country at 321 mg/LVery hard starts at 250 mg/L. At this level kettles scale up within weeks and a softener is a normal purchase in SG1. How hardness is measured
  • Right on the national average of 9 out of 10Most of the country's tested districts land within half a point of SG1. Compare every area

Next door

SG29.4 out of 10 · 321 mg/L

Questions about SG1 water

Is SG1 tap water safe to drink?

Based on the latest tests, SG1 (Stevenage) water scores 8.9/10, which is safe. 1 of 24 tested contaminants exceeded recommended levels. Water is supplied by Affinity Water.

What contaminants are in SG1 water?

We tested 24 contaminants in SG1 water. 1 were flagged, including Nitrite.

Who supplies water in SG1?

SG1 (Stevenage) is supplied by Affinity Water. You can view their full profile and compliance data on our supplier page.

Is SG1 water hard or soft?

Water in SG1 (Stevenage) has a hardness of 321 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 SG1?

With 1 contaminant above recommended levels in SG1, a water filter could help. A filter jug or under-sink filter can reduce most common contaminants. See our filter recommendations for your area.

Are there PFAS forever chemicals in SG1 water?

No PFAS (forever chemicals) result is attached to the tap-water tests for SG1, 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 SG1?

The Environment Agency rated the Stevenage Brook as poor for ecological health in its 2025 assessment, meaning the river is badly affected, with much of the expected wildlife missing. It is held back by fish, water plants and algae and insects and other small river life. 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 SG1, which is treated before it reaches homes.

Keep reading

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

River and groundwater readings near SG1

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
Dissolved Oxygen8.78 mg/LNone
Iron0.069 mg/L0.2 mg/L
pH7.5 pHNone
Temperature10.7 °CNone
Conductivity716 µS/cmNone
Ammonia0.073 mg/L0.5 mg/L
Nitrate0.46 mg/L50 mg/L
Hardness (as CaCO3)347 mg/LNone
Fluoride0.15 mg/L1.5 mg/L
Phosphate0.01 mg/LNone
PFAS (total)0.0076 µg/LNone

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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