Potable Water & Plumbing

Water safety tests required as part of AS/NZS 3498 WaterMark certification are:

• AS/NZS 4020: Testing of products for use in contact with drinking water Amendment No. 1 Revised text amendment
• AS 3498: Safety and public health requirements for plumbing products - Water heaters and hot-water storage tanks. Includes Legionella control method.

HPWHs must comply with AS/NZS 3498, which provides guidelines and requirements for managing Legionella risks in water heating systems.

Understanding Legionella: Legionella is a bacterium that can cause Legionnaires’ disease, a severe form of pneumonia. It thrives in warm water environments, making water heaters, including HPWHs, potential breeding grounds if not properly managed.

Legionella Compliance in AS/NZS 3498: AS/NZS 3498 outlines specific requirements for managing Legionella risks in water systems.

AS/NZS 3498 7.1 (j) offers two relevant control strategy options for managing Legionella:

1. At least 90% of the water in the storage tank is heated to 60degC for at least one single period of not less than 32 min in each 7 day period, or;
2. At least 45% of the water in the storage tank is heating to a minimum of 60degC daily.

HPWH Control Strategies

Compliance for the two options is achieved by employing one of the following methods:

1. If choosing option (i), 45% to 60degC daily, the HP sensor must have >45% volume above it, and the daily HP setpoint must be 60degC or greater.
2. If choosing option (ii), 90% to 60degC+ weekly, the HP or element sensor must have >90% volume above it, and the weekly setpoint must be 61degC or greater. The controller must employ one 90% heating cycle once per week.