Understand your PFAS laboratory report using current scientific guidance.
Adults typically drink about 30 mL of water per kilogram of body weight each day. Children generally drink about 35 mL/kg, so the estimated percentage is slightly higher.
This Version 1 Report Interpreter is based on the four PFAS used in the European Food Safety Authority (EFSA) Tolerable Weekly Intake.
There are thousands of PFAS chemicals. This Report Interpreter does not attempt to measure every PFAS. Instead, it follows the approach adopted by the European Food Safety Authority (EFSA) and recommended by Jersey's Independent PFAS Scientific Advisory Panel.
The four PFAS are:
Why only these four?
When EFSA carried out its major health assessment in 2020, these were the four PFAS for which the strongest human scientific evidence existed. They were selected because they:
For those reasons, EFSA based its health guidance on the combined exposure to these four PFAS.
The Jersey Independent PFAS Scientific Advisory Panel recommended using the same simple Sum of 4 approach because it is scientifically robust, transparent and internationally recognised.
Why is PFNA included?
PFNA is often found at lower concentrations than PFOS or PFOA, but scientific evidence shows it is biologically important. Some international regulatory systems consider PFNA relatively more potent when using Relative Potency Factor (RPF) methods.
This Version 1 Report Interpreter does not use Relative Potency Factors. It follows the simple Sum of 4 approach recommended by Jersey's Independent PFAS Scientific Advisory Panel.
Enter the Sum of 4 PFAS result from your laboratory report
If your laboratory report lists PFOS, PFOA, PFHxS and PFNA separately, simply add those four values together and enter the total below.
Pre-filled with the current Jersey Water annual average (12 ng/L). Overwrite it with your own water's value.
Current Jersey Water 2025 annual average (Sum of 4 PFAS): 12 ng/L. Source: Jersey Water Water Quality Report 2025.
If your water supplier already reports the sum of these four PFAS, simply enter that number. Do not enter a 'Total PFAS' value or a different PFAS group unless it specifically states it is the sum of PFOS + PFOA + PFHxS + PFNA.
For drinking water, 1 ng/L is exactly the same as 1 part per trillion (1 ppt), so no conversion is required.
Drinking this water alone could use about
Based on typical daily water intake for the selected age group.
EFSA Tolerable Weekly Intake (TWI): you can think of this as a weekly intake limit. Read EFSA's official explanation.
Keep drinking enough water to stay healthy. If your water contains PFAS, the solution is to reduce PFAS exposure, not reduce hydration.
All figures are the sum of PFOS, PFOA, PFNA and PFHxS. Recommended water intake is a hydration reference (30 mL per kg for adults, 35 mL per kg for children), not a limit.
Version 1 estimates drinking-water contribution using typical intake assumptions for adults and children. It does not model pregnancy, fetal exposure, breastfeeding, organ development, long-term PFAS accumulation or individual body burden. Those are planned for a future PFAS Exposure Explorer Version 2.
These two numbers have completely different purposes.
4 ng/L
This is the Independent PFAS Scientific Advisory Panel's recommended enforceable drinking-water standard. It applies only to the simple Sum of four PFAS:
10 ng/L
This is NOT the recommended drinking-water standard. Instead, it is a guidance value for the average Sum of 48 measurable PFAS.
If routine monitoring of the Sum of 48 PFAS reaches or exceeds 10 ng/L, the Panel recommends that this should trigger further investigation. It is an investigation trigger, not a replacement for the 4 ng/L drinking-water standard.
The Draft Fourth Scientific Report – Drinking Water, published in July 2026, recognised that new PFAS treatment systems cannot be installed overnight.
After reviewing international experience together with Jersey's practical constraints, the Independent PFAS Scientific Advisory Panel recommended that drinking water should achieve the 4 ng/L standard:
"As soon as is reasonably practicable, ideally within five years."
The Panel noted that some well-resourced programmes elsewhere may achieve implementation in around three years. However, Jersey may require longer because treatment technology must be selected, pilot tested, designed, procured, constructed and integrated into Jersey's water treatment system.
This recommendation does not mean waiting five years before taking action. It means beginning work immediately and achieving the 4 ng/L standard as quickly as reasonably practicable.
Regulatory methodology — not EFSA
EFSA's Tolerable Weekly Intake is a limit for total PFAS exposure from all sources.
When regulators turn that total-exposure limit into a drinking-water limit, they usually reserve only part of the total intake for water, because food, dust and other sources also contribute. This is called Relative Source Contribution (RSC).
The Jersey Independent Scientific Advisory Panel explains that many regulators allocate only part of the total tolerable PFAS intake to drinking water because food and other exposure sources also contribute. The report discusses examples including WHO, the US EPA and Sweden.
In simple terms: the full EFSA weekly limit is not normally allocated to drinking water alone. A drinking-water standard is usually set lower so there is room for exposure from food and other sources.
This does not change your estimate above. Different countries may use different allocation percentages when deriving drinking-water standards. Your estimate still shows how much of EFSA's total weekly intake would come from drinking water at the concentration you entered.
Source: Independent PFAS Scientific Advisory Panel for Jersey, Draft Fourth Scientific Report – Drinking Water, pp. 92–93.
Every figure used in this Report Interpreter is traceable to a published scientific or official source.
Scientific basis
[1]European Food Safety Authority (EFSA).
Risk to human health related to the presence of perfluoroalkyl substances in food.
EFSA Journal, 2020.
Tolerable Weekly Intake (TWI): 4.4 ng/kg body weight/week for the Sum of 4 PFAS (PFOA, PFOS, PFHxS and PFNA).
Jersey
[2]Jersey Water.
Water Quality Report 2025.
Average Sum of 4 PFAS in treated drinking water: 12 ng/L.
Average Sum of 48 PFAS: 31 ng/L.
[3]Independent PFAS Scientific Advisory Panel for Jersey
Panel members:
Dr Steve Hajioff
Professor Ian Cousins
Dr Tony Fletcher
Draft Fourth Scientific Report – Drinking Water (July 2026)
Final recommendations:
• Adopt an enforceable drinking-water standard of 4 ng/L for the simple Sum of 4 PFAS.
• Monitor the average Sum of 48 measurable PFAS.
• Use 10 ng/L for the Sum of 48 PFAS as a guidance value to trigger further investigation.
• Achieve 4 ng/L as soon as reasonably practicable, ideally within five years.
Government of Jersey
Independent PFAS Scientific Advisory Panel
Important
This Report Interpreter estimates PFAS exposure from drinking water only. Total PFAS exposure also comes from food, consumer products and other environmental sources.
This Report Interpreter has been developed independently in the public interest, to help people understand PFAS laboratory reports using current scientific guidance.
Continued development, scientific updates, maintenance, testing and educational resources all require ongoing support.
If you have found this Report Interpreter useful, please consider supporting its continued development.
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Medical disclaimer
Contact: waterawarenessjersey@gmail.com
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Note: This app uses ng/L (nanograms per litre), the standard unit in Europe. In the USA, this is often referred to as ppt (parts per trillion). 1 ng/L = 1 ppt.