Tap water in L21, SeftonSafe to drink.Moderately soft.
Supplied by United Utilities. 2,004 samples, 16 substances, latest on 30 December 2024. Everything is inside the legal limit, and nothing comes close to it.
9.4 / 10
The tank is as full as the score. The specks are the minerals that make water hard.
What to do about it
ZeroWater 12-Cup Ready-Pour
£40typical price
Households concerned about PFAS and heavy metals
Waterdrop 10UA Under Sink
£70typical price
High-volume under-sink filtration without RO complexity
BRITA Marella XL + MAXTRA PRO
£25typical price
Basic chlorine and taste improvement on a budget
We earn a commission if you buy through these links, at no extra cost to you. It never changes which product we put first. How we make money
What's in a glass of L21 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.
Trihalomethanes came closest to a limit, at 25% of it. 15 of 16 substances used under a quarter of theirs.
- Trihalomethanes25%
- Nitrate13%
- Ammonia11%
- Nickel11%
- Antimony6%
- Bromate6%
- Lead6%
- Turbidity4%
- Iron3%
- Aluminium3%
- Selenium2%
- Nitrite2%
- Cadmium2%
- Chromium2%
- Manganese<1%
- Copper<1%
All 16 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Iron | 0.007 mg/L | 0.2 mg/L | 3% |
| Trihalomethanes | 0.025 mg/L | 0.1 mg/L | 25% |
| Manganese | 0.00045 mg/L | 0.05 mg/L | <1% |
| Turbidity | 0.16 NTU | 4 NTU | 4% |
| Aluminium | 0.00688 mg/L | 0.2 mg/L | 3% |
| Copper | 0.0000512 mg/L | 2 mg/L | <1% |
| Nickel | 0.00212 mg/L | 0.02 mg/L | 11% |
| Lead | 0.00059 mg/L | 0.01 mg/L | 6% |
| Nitrate | 6.51 mg/L | 50 mg/L | 13% |
| Nitrite | 0.0098 mg/L | 0.5 mg/L | 2% |
| Ammonia | 0.054 mg/L | 0.5 mg/L | 11% |
| Bromate | 0.0006 mg/L | 0.01 mg/L | 6% |
| Cadmium | 0.00009 mg/L | 0.005 mg/L | 2% |
| Chromium | 0.00083 mg/L | 0.05 mg/L | 2% |
| Antimony | 0.00031 mg/L | 0.005 mg/L | 6% |
| Selenium | 0.00085 mg/L | 0.04 mg/L | 2% |
86mg of limescale minerals in every litre
Soft water. Kind to kettles, boilers and skin
You will not need a softener here, and you will use less soap and detergent than most of England.
Your river is the Alt US Bull Bridge, rated moderate
The Environment Agency rated the Alt US Bull Bridge as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. It is held back by fish, insects and other small river life and phosphate. 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
36
forever-chemical detections in nearby rivers and groundwater
At 4 sites. The highest was 6:2 FTSA at 0.12 µg/L, at Mossock Hall Farm SD40/144, 9.5 km away, in September 2025. These are river and borehole samples, not tests of your tap water.
Every PFAS sample around Liverpool · Which filters remove PFAS · PFAS explained
L21 in short
Tap water in L21 (Sefton) is supplied by United Utilities in the Sefton Central zone and scores 9.4 out of 10, against an England and Wales average of 9.0. None of the 16 tested substances came close to a limit. The latest sample is from 30 December 2024.
- The cleanest tap water of the 12 areas tested in SeftonL21 scores 9.4 out of 10, ahead of L23 in second place on 9.4.
- PFAS found at 4 monitoring sites within 10 kmThose are river and groundwater samples, not tap water. The highest was 6:2 FTSA about 9.5 km away. What was measured
- Nothing tested came within 40% of its legal limitThe highest was Trihalomethanes at 25% of the 0.1 mg/L maximum. See every reading
Questions about L21 water
Is L21 tap water safe to drink?
Based on the latest tests, L21 (Sefton) water scores 9.4/10, which is safe. 0 of 16 tested contaminants exceeded recommended levels. Water is supplied by United Utilities.
What contaminants are in L21 water?
We tested 16 contaminants in L21 water. None exceeded recommended safe levels. 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 L21?
L21 (Sefton) is supplied by United Utilities. You can view their full profile and compliance data on our supplier page.
Is L21 water hard or soft?
Water in L21 (Sefton) has a hardness of 86 mg/L CaCO3, which is classified as moderately soft. This is a moderate hardness level.
Should I use a water filter in L21?
L21 water scored 9.4/10 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 L21 water?
The tap-water tests we hold for L21 do not include a PFAS result. Environment Agency monitoring found PFAS in 36 river and groundwater samples from 4 sites within 10 km of L21, the highest being 6:2 FTSA at 0.12 µg/L about 9.5 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 L21?
The Environment Agency rated the Alt US Bull Bridge as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. It is held back by fish, insects and other small river life and phosphate. 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 L21, 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
- Is UK Tap Water Safe?Everything you need to know about tap water safety in the UK
- Best Water Filters UKEvery filter type compared on what it actually removes
PFAS explainedHow to test your waterBest water filtersFilter shower headsWater testing kitsUK water rankingsWater hardness checkerWater hardness map
River and groundwater readings near L21
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.
| Substance | Reading | Drinking water limit |
|---|---|---|
| pH | 7.51 pH | None |
| Temperature | 16 °C | None |
| Conductivity | 623 µS/cm | None |
| Ammonia | 0.077 mg/L | 0.5 mg/L |
| Nitrate | 14 mg/L | 50 mg/L |
| Nitrite | 0.064 mg/L | 0.5 mg/L |
| Phosphate | 0.32 mg/L | None |
| Dissolved Oxygen | 8.72 mg/L | None |
| Cadmium | 0.000301 mg/L | 0.005 mg/L |
| Hardness (as CaCO3) | 81 mg/L | None |
| Zinc | 0.0385 mg/L | None |
| Nickel | 0.00172 mg/L | 0.02 mg/L |
| Aluminium | 0.0105 mg/L | 0.2 mg/L |
Get alerts for your area
We'll email you when water quality data changes for L21.