4.1: Metal and metalloid chemicals leaching from plumbing products

(endorsed 2025)

Background

Section 9.6 of the Guidelines outlined that some plumbing products used within premises, such as residential buildings, hospitals and schools, have the potential to leach chemicals. This can also occur in outdoor plumbing networks such as drinking fountains at municipal parks, beachfront areas, outdoor plazas or outdoor sporting facilities. This information sheet covers metal and metalloid chemicals that under certain conditions can leach from plumbing products into drinking water. This is likely to occur past the point of water supply (i.e. the water meter) as leaching most likely occurs within the in-premise plumbing system. For example, if water has been sitting in contact with metallic plumbing products for extended periods of time, then metals from the plumbing products can leach out and dissolve into the drinking water. Additionally, higher concentrations of metals can leach out and dissolve into hot water systems compared to cold water systems.

Other factors that can contribute to leaching of chemicals include temperature, water quality (e.g. pH, alkalinity, corrosivity and hardness), plumbing fittings and fixtures (age, material type and galvanic corrosion) and hydraulics (flow rates, stagnation times and water turnover) (Taylor et al. 2018). Corrosion control, including monitoring pH and hardness, is noted in Section 9.6. Rainwater may also dissolve more metals from plumbing products due to rainwater being slightly acidic (and having very low hardness) (enHealth 2021a, 2021b).

Leaching of chemicals into drinking water can increase the likelihood of exposure to these chemicals and increase the risks to public health. The leaching of lead from copper alloys in plumbing has historically received the most attention, given the known health effects of lead exposure (see the Lead Fact Sheet and NHMRC 2015). In light of concerns about the health effects of lead, there have been efforts to reduce exposure by reducing the allowable limit of lead in plumbing materials (ABCB 2023). As a result, there is an increasing availability of alternative plumbing products (such as lead free plumbing products) on the Australian market.

The National Construction Code (NCC), Volume Three - Plumbing Code of Australia (PCA), developed and maintained by the Australian Building Codes Board (ABCB), requires from 1 May 2026 that copper alloy plumbing products used for conveying drinking water must limit the allowable lead content to a weighted average of not more than 0.25%. Products that meet this requirement will be known as "lead free". This is to ensure that metals do not leach into the water at concentrations higher than health-based guideline values. Compliant products will be marked with a “Lead Free” watermark under the certification scheme. Copper alloy products that are required to comply with these provisions, include: fittings, valves, backflow prevention devices, taps, mixers, water heaters, water dispensers (boiling and cooling units) and water meters (ABCB 2022).

There are many other metals of concern that may be present in plumbing products such as antimony, cadmium, chromium, copper and nickel (enHealth 2021b). Further information on the health effects of these metals is provided in the relevant Fact Sheets in Part V of these Guidelines. Various other materials have been studied worldwide as a replacement for lead in copper alloys. These materials include bismuth, selenium, silicon, graphite, indium, gallium and manganese/zinc. At this stage, limited information is available on the composition of substitute plumbing products and what is available on the Australian market. In the United States of America, the most common substitutes for lead in copper alloys are bismuth and silicon (ABCB 2021).

Risks from exposure to metal and metalloid chemicals leaching from plumbing products

While the introduction of lead free plumbing products will reduce the risk of exposure to lead leaching into drinking water, it is important to confirm that any chemicals used to replace lead in plumbing products do not leach into water at unsafe levels. In the absence of information on specific copper alloys, the available information on the relevant chemicals used to replace lead in plumbing products (that may reasonably be expected to leach into drinking water) should be considered when setting acceptable limits in lead replacement plumbing products. Further information on the health effects of specific chemicals, including calculations for health-based guideline values or levels at which health effects are not expected to occur, are provided in the relevant Fact Sheets in Part V of these Guidelines.

As new information and data on the types and composition of plumbing products becomes available, guidance around the potential risks to health from chemicals leaching from plumbing products can be refined and updated.

Review of bismuth, selenium and silicon copper alloys

A review of the existing scientific evidence was undertaken for several copper alloy formulations that had been identified as potential lead replacements in plumbing products, specifically bismuth, selenium, and silicon (SLR 2023a, 2023b and 2023c). The review found little to no data to quantify the nature or levels of chemicals that may leach into drinking water from these copper alloys, whether in distribution systems or within premises (i.e. beyond the water meter). More information is needed on the forms of bismuth, selenium or silicon in water, and leachates, as well as potential exposure concentrations.

The available toxicological information for individual chemicals that may reasonably be expected to replace lead in copper alloys was instead used to derive health-based guideline values for bismuth and silicon, and to revise the health-based guideline value for selenium. The derivation of these values, including uncertainty factors and assumptions, are provided in the relevant Fact Sheets for bismuth, selenium and silicon (See Part V Physical and chemical characteristics).

Reducing exposure to metal and metalloid chemicals leaching from plumbing products

There are a number of regulatory measures already in place in Australia to preventatively manage health risks associated with plumbing products and to help ensure water at the tap is safe. For example, by ensuring plumbing products are safe for use in drinking water, the health risks can be reduced before a product is available on the market. From 1 May 2026, all new plumbing installations conveying drinking water are required to use products that are compliant with the lead free requirements of the Plumbing Code of Australia (ABCB 2022). These testing standards use the health-based guideline values described in these Guidelines to determine whether any leaching from the plumbing products is acceptable.

Section 9.6 of these Guidelines provides further information on:

• roles and responsibilities for managing water quality in-premises such as corrosion control including monitoring pH and hardness

• ways that water suppliers can help to reduce risks.

The introduction of lead free regulations for plumbing materials that come into contact with drinking water aims to reduce the potential health risks from lead leaching from plumbing products. In most circumstances, it will also reduce the need for additional measures to reduce exposure to lead within a building, such as preventative flushing regimes.

In instances where there is uncertainty about the water quality within a building (e.g. after drinking water has been sitting stagnant in a school plumbing system during a holiday break), additional measures can be taken to reduce potential risks to health.

Flushing

In the absence of in-premises water treatment options, reducing potential exposure to chemicals that may leach from plumbing products in households can be achieved at the tap by (enHealth 2021b):

• only using water from cold taps for drinking and food preparation (except for water from devices used for preparation of tea and coffee)

• flushing cold water taps for at least 10 seconds first thing in the morning to draw fresh water through the tap

• flushing cold water taps used for drinking and food preparation for at least 2 minutes after periods of non-use of more than 48 hours (such as when returning from holidays).

Flushed water can be collected and used for washing, bathing, general hygiene and garden irrigation.

As young children are the most at risk from adverse health effects associated with exposure to metals, it is recommended that facilities take a proactive approach to risk reduction. Reducing potential exposure to chemicals that may leach from plumbing products in schools, preschools and childcare centres can be achieved by following preventative household flushing protocols as listed above, and by (enHealth 2021b):

• flushing all drinking water outlets and water fountains / bubblers that are used for drinking and food preparation for at least 10 seconds to clear any water that has been sitting in the individual plumbing fittings

• flushing a drinking water outlet furthest away from the incoming supply (i.e. the water meter) for at least 2 minutes after periods of non-use of more than 7 days. Flushing for a longer period (up to 5 minutes) or selecting outlets at a number of locations may be required in facilities with larger water distribution systems in order to draw fresh water from the incoming supply.

In other buildings with vulnerable occupants, such as pregnant women and infants, flushing frequency and duration will depend on the likelihood of stagnation, and the length and complexity of the plumbing system. Taps that are unused for several days or more should be flushed for at least 2 minutes if they are used for drinking. In facilities that do not provide overnight services, taps used as a source of drinking water and drinking water fountains should be flushed for at least 10 seconds each morning. As good practice, building and asset managers, including residential strata body corporate managers, should identify all drinking water outlets to be flushed, the frequency of when flushing is to occur and record when flushing has occurred.

Extensive flushing is also advisable towards the end of commissioning of newly constructed or renovated plumbing systems. This is advisable because plumbing works can leave significant amounts of “swarf” or metal filings within the drinking water pipes. Flushing to remove these needs to be done after aerators or flow restrictors are removed to ensure swarf is not entrapped within drinking water outlets.

Further information can be found in enHealth (2021b).

Treatment

Some in-premises water treatment units, such as filtration or reverse osmosis units, may be effective at removing chemicals from drinking water in plumbing systems. However, this can vary depending on the type and form of the chemical (dissolved or particulate) and where the unit is connected into the plumbing system. Advice from a water professional, relevant health authority and/or drinking water regulator should be sought to determine if water treatment units are appropriate for the given context. As water treatment units require regular maintenance and replacement, they should not be viewed as a permanent solution to manage elevated levels of metals or metalloids that may have leached from in-premise plumbing products. Water treatment units that involve filtration may also trap particles, allowing metals to later dissolve from the particles into the drinking water. Buyers of point-of-use filtration devices should look for filters that have been validated to remove metals. Manufacturers’ instructions regarding installation, operation and maintenance should be followed to ensure the filtration units remain effective.

In-premise sampling

The Environmental Health Standing Committee of the Australian Health Protection Committee (formerly the Australian Health Protection Principal Committee) has published Reducing exposure to metals in drinking water from plumbing products, 2021 that details all considerations and recommended methodologies for taking samples (enHealth 2021b).

The water sampling methods described below will help to identify metals of concern in a plumbing system. They can also help to find the sources of those metals. Proactive testing of drinking water for metals is not generally required unless there are specific concerns (see below).

A sampling program to test for metals should be initiated:

• during commissioning of new or renovated buildings, excluding sole occupancy dwellings, to ensure the system can supply safe water (e.g. new hospitals or large multi-occupancy commercial buildings)

• if there is evidence of elevated metals in the water supply (e.g. metallic taste, discoloured water, brown or blue/green copper staining of plumbing products such as basins or toilet bowls) or suspected elevated metals from the use of non-compliant plumbing products.

A sampling program to test for metals could be useful in certain circumstances such as:

• verifying/validating the success of a flushing program

• assessing whether a flushing regime is required

• identifying outlets that may require inclusion in a flushing program.

There is no single water sampling method for metals in drinking water that is suitable for all circumstances. The sampling method chosen is dependent on the objective. AS/NZS 5667.5 (Standards Australia 1998) is well designed for collecting drinking water samples from treatment plants and distribution systems but has limitations when collecting drinking water samples within buildings (Health Canada 2019) and specifically when the intent of a sample is to determine metal influences from plumbing products. The scope of enHealth (2021b) guidance covers the water sampling methodologies for four separate objectives:

• Incoming water supply sampling – to determine the concentration of metals from the incoming water supply. A flushed sample is the most appropriate methodology.

• Building commissioning – to determine the presence of metals in a building as part of the commissioning process. The 6-hour stagnation sample is the most appropriate methodology.

• Screening sampling – to determine the presence of metals in drinking water within the plumbing system. The random daytime sample is the most appropriate methodology.

• Investigative sampling – to identify the potential source of metals in drinking water within a plumbing system after non-compliant results are generated from the 6-hour stagnation or random daytime sampling methodology. The 30-minute stagnation is the most appropriate methodology.

Further technical details are provided in enHealth (2021b).

Plumbing systems are site-specific and advice should be sought from water professionals, local water suppliers, the relevant health authority and/or drinking water regulator before implementing a sampling program. The design and implementation of a water sampling program is complex and careful planning should be undertaken to ensure that meaningful results are generated.

References

ABCB (2021). Lead in plumbing products in contact with drinking water. Final Regulation Impact Statement 2021. Australian Building Codes Board, July 2021.

ABCB (2022). National Construction Code 2022 Volume 3 – Plumbing Code of Australia. Commonwealth of Australia and the States and Territories 2022, published by the Australian Building Codes Board.

ABCB (2023). WaterMark Certification Scheme – Notice of Direction 2022/1.1: Acceptable copper alloys for the manufacture of Lead Free plumbing products. Australian Building Codes Board, May 2023.

enHealth (2021a). enHealth Guidance Statement: Lead in drinking water from some plumbing products. Environmental Health Standing Committee (enHealth) of the Australian Health Protection Principal Committee, October 2021.

enHealth (2021b). enHealth Guidance – Reducing exposure to metals in drinking water from plumbing products. Environmental Health Standing Committee (enHealth) of the Australian Health Protection Principal Committee, December 2021.

Health Canada (2019). Guidelines for Canadian Drinking Water Quality: Guideline Technical Document – Lead. Water and Air Quality Bureau, Healthy Environmental and Consumer Safety Branch, Health Canada, March 2019.

NHMRC (2015). NHMRC Statement: Evidence on the Effects of Lead on Human Health. National Health and Medical Research Council, Australian Government, 2015.

SLR (2023a). Evidence Evaluations for Australia Drinking Water Guidelines Chemical Fact Sheets – Lead Replacements in Plumbing – Bismuth Evaluation Report. SLR Consulting Australia Pty Ltd. Report prepared for the National Health and Medical Research Council, December 2023.

SLR (2023b). Evidence Evaluations for Australian Drinking Water Guidelines Chemical Fact Sheets – Lead Replacements in Plumbing – Silicon Evaluation Report. SLR Consulting Australia Pty Ltd. Report prepared for the National Health and Medical Research Council, December 2023.

SLR (2023c). Evidence Evaluations for Australian Drinking Water Guidelines Chemical Fact Sheets – Lead Replacements in Plumbing – Selenium Evaluation Report. SLR Consulting Australia Pty Ltd. Report prepared for the National Health and Medical Research Council, November 2023.

Standards Australia (1998). Water quality - Sampling - Part 5: Guidance on sampling of drinking water used for food and beverage processes, ISO 5667-5:1998, February 1998.

Taylor MP, Harvey PJ, Morrison AL (2018). Lead in Plumbing Products and Materials. Macquarie University, NSW, Australia. ISBN: 978-1-74138-468-0.