Radon in drinking water ingestion dose calculator

Use this calculator to estimate the committed effective dose from ingesting radon-222 dissolved in drinking water. It can apply the ICRP Publication 137 adult Reference Worker ingestion coefficient or the age-dependent public ingestion coefficients published in ICRP Publication 158.

The estimate covers ingestion only. It does not calculate dose from inhaling radon released from water during showering, bathing, washing, cooking, treatment or other uses. In many circumstances, inhalation of radon released into indoor air is the more important exposure pathway.

Choose the assessment category carefully

Select Adult Reference Worker — ICRP Publication 137 where the adult Reference Worker ingestion coefficient is required for the assessment. Selecting this coefficient does not by itself determine whether the intake is statutory occupational exposure or should be included in a formal dose record.

Select Member of the public for an environmental or public drinking-water assessment. The calculator then applies the ICRP Publication 158 coefficient for the selected age group.

Use a representative water result

Use a result obtained using an appropriate radon-in-water sampling and analytical method. The sample should normally represent the water at the point of consumption. A groundwater-source, borehole, tank or treatment-inlet result may not represent the concentration actually consumed.

Radon can be lost through aeration, agitation, sample headspace, storage, transport delay and inappropriate handling. These losses can make an analytical result artificially low. Record where and when the sample was collected and whether any treatment or storage occurred before the sampling point.

Water-consumption assumptions

Worker presets assume 230 working days per year. Public presets are generic screening assumptions. For public calculations, the selected age group sets an initial volume:

  • infant, birth to under 1 year — 0.75 L/day;
  • child, 1–12 years — 1 L/day;
  • young person, over 12–17 years — 2 L/day; and
  • adult, over 17 years — 2 L/day.

These values are starting assumptions rather than recommended individual consumption rates. Replace them with the actual annual volume consumed from the assessed supply where reliable information is available.

Scope: The calculator covers radon-222 ingestion only. It does not assess radium or other radionuclides, water quality generally, inhalation dose, or compliance with drinking-water legislation.

Uses the ICRP Publication 137 adult Reference Worker ingestion dose coefficient for radon-222. Selecting this coefficient does not by itself determine whether an intake is statutory occupational exposure or should form part of a formal dose record.

Choose the concentration unit
Bq·L⁻¹

Enter a concentration representative of the water at the point of consumption. Radon can be lost through aeration, headspace, storage and delay, so use a result from an appropriate sampling and analytical method. All calculations are performed in Bq·L⁻¹.

Worker presets assume 230 working days per year. Choose a preset or enter a more accurate annual amount below.

litres/year

Include only water consumed at approximately the concentration entered above.

How the calculation works

The annual activity of radon-222 ingested is calculated as:

Annual activity ingested (Bq) = water concentration (Bq/L) × annual water consumption (L/year)

The committed effective dose is then:

Committed effective dose (Sv) = annual activity ingested (Bq) × ingestion dose coefficient (Sv/Bq)

The result is displayed in microsieverts and millisieverts. The expandable calculation details show the annual intake, coefficient used and complete worked calculation.

Ingestion dose coefficients

Adult Reference Worker

The worker option uses the ICRP Publication 137 adult Reference Worker ingestion coefficient for radon-222:

6.9 × 10⁻¹⁰ Sv/Bq

Members of the public

The public option uses the following ICRP Publication 158 age-dependent committed effective dose coefficients:

  • infant, birth to under 1 year — 4.0 × 10⁻⁹ Sv/Bq;
  • child, 1–2 years — 2.1 × 10⁻⁹ Sv/Bq;
  • child, over 2–7 years — 1.2 × 10⁻⁹ Sv/Bq;
  • child, over 7–12 years — 8.6 × 10⁻¹⁰ Sv/Bq;
  • young person, over 12–17 years — 7.5 × 10⁻¹⁰ Sv/Bq; and
  • adult, over 17 years — 7.7 × 10⁻¹⁰ Sv/Bq.

Drinking-water values in Scotland, England and Wales

Across Great Britain, drinking-water rules use 100 Bq/L as the radon parametric value. This applies in Scotland, England and Wales, although the detailed legal provisions and responsible authorities differ according to the country and whether the supply is public, private or bottled.

The 100 Bq/L value primarily triggers confirmation, investigation and appropriate advice. A result at or above this value does not automatically mean that treatment must be installed in every case. The result should first be confirmed as representative and the supply investigated.

Where radon exceeds 1,000 Bq/L, drinking-water rules treat remedial action as justified without further consideration. Prompt advice should be obtained from the relevant water regulator or local authority and from competent water-treatment and radiation-protection specialists.

These are concentration-based drinking-water values. They are not applied by comparing the calculator’s estimated ingestion dose with a dose limit.

Radon released from water into indoor air

Radon dissolved in water can be released during showering, bathing, washing, cooking, aeration and other uses. As a broad population-average relationship, water containing 1,000 Bq/L may add approximately 100 Bq/m³ to indoor air when used. Actual transfer varies greatly with water use, building volume, ventilation, temperature, agitation and the configuration of the water system.

This approximate relationship should not be used instead of measuring indoor-air radon. Where water contains radon at or above 100 Bq/L, consider a representative indoor-air measurement if one has not already been completed.

Treatment considerations

Point-of-entry aeration can remove radon before water is distributed, but the extracted gas must be discharged to a suitable outdoor location where it will not re-enter the building or expose workers and occupants.

Granular activated carbon can also reduce radon, but the media may accumulate radioactivity. This can create radiation-protection, maintenance, handling and disposal considerations, particularly at higher concentrations or after extended use.

Treatment should be selected and designed for the individual supply by a competent specialist. The treated water should be re-tested to confirm performance, and ongoing monitoring and maintenance may be required.

Interpretation and limitations

This calculator provides an indicative ingestion-dose estimate based on the values entered. Its reliability depends on the concentration and consumption assumptions being representative.

It does not:

  • estimate inhalation dose from radon released into indoor air;
  • assess radium, uranium or other radionuclides;
  • determine whether water is wholesome or safe to drink;
  • replace statutory sampling, investigation or enforcement arrangements; or
  • replace advice from the relevant water authority, laboratory, Radiation Protection Adviser or competent treatment specialist.

References and calculation basis

 

Calculator version: 1.2
Calculation basis reviewed: July 2026