SANS 241-1: A Definitive drinking water quality standard

SANS 241-1 is the definitive drinking water quality standard in South Africa and water compliant with the stipulations thereof is deemed safe for consumption. A draft has been released for the 2021 edition 7 and is open for public comment until 29 June 2022. The proposed changes are outlined below.

This document combines the requirements of what was previously Part 1 and Part 2 of SANS 241-1: 2015 and includes an expanded section on water quality risk assessments. In the draft version this section has been divided into three subsections:

  • hazard identification,

  • risk analysis and

  • risk verification

Previously, risk assessments were discussed in broader terms under “Requirements for water quality risk assessments” and “Interpretation of water quality risk assessments”.

Under Hazard identification, more considerations have been included, including:

  • source of water and possible source of contamination,

  • treatment processes,

  • size and age of the water supply system,

  • parameters that might enter/form in the distribution system,

  • concentration changes over time or at different changes and

  • historical data.

These more robust guidelines for hazard identification should be welcomed as they now consider not only the water sourced and supplied but also external factors that may have a detrimental impact on the supply of water.

The new version specifies that risk analysis shall be ongoing with stipulations for when they will be performed and when they will be repeated and includes explanatory notes with scenarios that should be included in any considerations.

Five tables with concentration/level limits are included in the new draft edition:

Table 1 – Mandatory process risk indicators

The mandatory process risk indicators include physical parameters, microbiological indicators and operational indicators such as disinfectant residuals, treatment chemicals and treatment.

Table 2 – Microbiological indicators

The microbiological indicators now also include viruses (thought monitoring is not compulsory), Clostridium perfringens (for water reuse/reclamation systems using filtration and membrane technologies), and intestinal enterococci (for treatment systems receiving saline/brackish raw water with TDS ≥ 1000mg/L.

Table 3 – Physical, organoleptic and inorganic chemical parameters

Taste and odour have been added as a physical/aesthetic parameters while changes to the chemical parameters include:

  • the removal of the acute health limit for Sulfate as SO42-

  • The addition of limits for nitrate as NO3 and nitrite as NO2

  • The lowering of the limit for Zinc

  • A standard limit for Ammonia is N to negate operation risk

  • Changes to the limits of the following micro-parameters

o Aluminium as Al

o Barium as Ba

  • The removal of the following micro-parameters

o Cyanide (recoverable) as CN­-

o The chronic health limit for Iron as Fe and Manganese as Mn concentrations

  • The addition of indices to determine the scaling or corrosion potential of the water for the protection of infrastructure

  • The addition of radioactivity as a parameter to be monitored.

Table 4 – Organic chemical parameters

While there were eight organic determinants stipulated in the 2015 version of the standard, the draft version has expanded this to 12 parameters that include agricultural chemicals, natural chemicals, pharmaceuticals, and industrial chemicals.

Table 5 – Disinfection residuals and disinfection treatment byproducts

Table 5 includes disinfection residuals and by-products that are to be considered mandatory process indicators for certain water treatment systems as indicated by the additional information in column 5.

These tables include, like the tables in the previous edition, the parameter, the risk, the units and the standard limits. There is also an additional column with additional information on the monitoring requirements, interpretation of the results, as well as possible actions that can be taken if the limits are exceeded.

The frequency of the monitoring section has also been expanded to include the new parameters and changes were made to the monitoring frequencies of a few parameters.

The standard now also includes clauses about the monitoring of mobile tankers; monitoring static tanks; expanded stipulations on the management of drinking water quality non-compliances, and handling numeric uncertainties.

This standard has fewer pages than the previous version (Parts 1 and 2) and does not include example risk and compliance calculations as found in Annexes A and B of SANS 241-2:2015. It does, however, feel like a robust standard with guidance on risk-based thinking that encourages a more holistic approach in the identification of hazards that may lead to detrimental health effects as well as a failure in the supply of safe drinking water.

All stakeholders are encouraged to comment on this draft and have their say in the setting of these standards. A copy can be obtained by registering at the following link and submitting their comments according to the instructions provided on the first page of the draft copy.

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