Tap water in E4, Waltham Forest2 results are over the limit.Very hard.
Supplied by Thames Water. 15 substances, latest on 3 September 2026. Ammonia and Turbidity came in above the legal limit. Everything else passed.
6.3 / 10
The tank is as full as the score. The specks are the minerals that make water hard.
What to do about it
Osmio PRO-III Ultimate Whole House
£499typical price
Removes turbidity, the result that stood out in E4.
Stop the limescale
At 270 mg/L a softener is the only thing that stops limescale. Filters do not soften water.
BWT E1 Single Lever
£250typical price
Removes turbidity, the result that stood out in E4.
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What's in a glass of E4 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.
Ammonia is over its legal limit, at 360% of it.
- Ammonia360%
- Turbidity102%
- Nitrite100%
- Iron45%
- Nickel17%
- Arsenic13%
- Nitrate6%
- Cadmium<1%
- Copper<1%
- pH 7.7 pH
- Temperature 18.6 °C
- Conductivity 743 µS/cm
- Phosphate 1.4 mg/L
- Dissolved Oxygen 4.35 mg/L
- Zinc 0.0039 mg/L
All 15 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Ammonia | 1.8 mg/L | 0.5 mg/L | 360% |
| Nitrite | 0.5 mg/L | 0.5 mg/L | 100% |
| Turbidity | 4.1 NTU | 4 NTU | 102% |
| pH | 7.7 pH | No legal limit | – |
| Temperature | 18.6 °C | No legal limit | – |
| Conductivity | 743 µS/cm | No legal limit | – |
| Nitrate | 2.8 mg/L | 50 mg/L | 6% |
| Phosphate | 1.4 mg/L | No legal limit | – |
| Dissolved Oxygen | 4.35 mg/L | No legal limit | – |
| Cadmium | 0.000028 mg/L | 0.005 mg/L | <1% |
| Zinc | 0.0039 mg/L | No legal limit | – |
| Nickel | 0.0033 mg/L | 0.02 mg/L | 17% |
| Arsenic | 0.0013 mg/L | 0.01 mg/L | 13% |
| Copper | 0.0023 mg/L | 2 mg/L | <1% |
| Iron | 0.091 mg/L | 0.2 mg/L | 45% |
270mg of limescale minerals in every litre, typical for the E area. E4 has no reading of its own.
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.
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Your river is the Ching Brook, rated moderate
The Environment Agency rated the Ching Brook as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. It is held back by ammonia, fish and dissolved oxygen. 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
475
forever-chemical detections in nearby rivers and groundwater
At 8 sites. The highest was 6:2 FtSAB at 0.016 µg/L, at Lee at Carpenters Rd, 8.8 km away, in January 2026. These are river and borehole samples, not tests of your tap water.
Every PFAS sample around London · Which filters remove PFAS · PFAS explained
E4 in short
Tap water in E4 (Waltham Forest) is supplied by Thames Water in the Waltham Forest Central zone and scores 6.3 out of 10, against an England and Wales average of 9.0. 3 of 15 tested substances were close to or over a limit. The latest sample is from 3 September 2026.
- Ammonia was measured at 1.8 mg/L, 3.6 times the UK limitIt is the furthest over its limit of the 3 substances flagged here. See the full results
- The lowest score of the 4 areas tested in Waltham ForestE4 scores 6.3 out of 10. The best in Waltham Forest, E11, scores 8.5.
- Every one of the 7 neighbouring districts scores higherEN3 next door scores 8.8, against 6.3 here. Supply zones, not distance, explain the gap. See EN3
Questions about E4 water
Is E4 tap water safe to drink?
Based on the latest tests, E4 (Waltham Forest) water scores 6.3/10, which is mostly safe but has some issues. 3 of 15 tested contaminants exceeded recommended levels. Water is supplied by Thames Water.
What contaminants are in E4 water?
We tested 15 contaminants in E4 water. 3 were flagged, including Ammonia, Nitrite, Turbidity. PFAS (forever chemicals) were also measured in rivers and groundwater within 10 km, though not in the tap-water tests themselves.
Who supplies water in E4?
E4 (Waltham Forest) is supplied by Thames Water. You can view their full profile and compliance data on our supplier page.
Is E4 water hard or soft?
No hardness reading has been published for E4 itself. Across the E postcode area the typical value is 270 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 E4?
With 3 contaminants above recommended levels in E4, a water filter could help. A reverse osmosis or activated carbon filter is recommended for PFAS removal. See our filter recommendations for your area.
Are there PFAS forever chemicals in E4 water?
The tap-water tests we hold for E4 do not include a PFAS result. Environment Agency monitoring found PFAS in 475 river and groundwater samples from 8 sites within 10 km of E4, the highest being 6:2 FtSAB at 0.016 µg/L about 8.8 km away. These are environmental samples, not tests of tap water. The UK currently has no legal limit for PFAS in drinking water; the Drinking Water Inspectorate uses a 0.1 µg/L guideline for individual compounds. Reverse osmosis filters can reduce PFAS levels.
How clean is the river near E4?
The Environment Agency rated the Ching Brook as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. It is held back by ammonia, fish and dissolved oxygen. 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 E4, which is treated before it reaches homes.
Keep reading
- Best Filter for PFAS RemovalThe filters with independent certification to remove forever chemicals
- PFAS Forever ChemicalsWhat PFAS are and how to reduce your exposure at home
- Best Water Softener UKHarvey, Kinetico, BWT, Monarch and Water2Buy compared, with real costs
- Do I Need a Water Softener?The hardness bands, the symptoms, and a postcode check
- UK Water Hardness MapIs your water hard or soft, and does it matter?
- Best Water Filters UKEvery filter type compared on what it actually removes
- Do I need a water softener?The hardness bands, the symptoms, and when the answer is no
- Best water softener UKHarvey, Kinetico, BWT, Monarch and Water2Buy compared
- Water softener costUnit, fitting and salt, and how long the payback takes
- Installation explainedWhere it goes, the bypass tap, the drain, DIY or plumber
- Harvey vs KineticoThe two premium twin-cylinder brands, side by side
- Softener salt guideTablet, block or granular, and how much you get through
- Salt-free softenersConditioners and electronic descalers, honestly assessed
PFAS explainedNitrate levelsHow to test your waterBest water filtersFilter shower headsWater testing kitsUK water rankingsWater hardness checkerWater hardness map
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