Rainwater harvesting and reuse is the process of capturing and storing rainwater for non-potable purposes, such as irrigation, toilet flushing, and industrial use. The rainwater is collected from roofs, stored in tanks, filtered, and treated before reuse.

Such systems are increasingly being adopted in both residential and commercial buildings to conserve water, reduce costs, and minimize environmental impact. To ensure these systems perform optimally over time, regular maintenance is essential.

Gutters and Downpipes

• Inspection for Blockages and Debris: Gutters and downpipes should be inspected for accumulated leaves, dirt, and debris that could block the flow of water. This blockage may cause overflow, which could potentially damage the building’s structure or foundations. Cleaning should be done at least once or twice a year, but more frequently if the property is surrounded by trees or experiences heavy rainfall.
• Check for Leaks and Cracks: Regularly check for leaks, cracks, or corrosion in the gutters and downpipes. Any damage should be sealed, or the affected sections replaced, to prevent further deterioration and ensure efficient water flow.
• Ensure Proper Alignment and Stability: Gutters and downpipes must be correctly aligned and supported. Misalignment may lead to water overflow or pooling around the building’s base, potentially causing water damage or foundation issues.
• Inspect for Ice or Frost Damage (in colder climates): In areas prone to freezing temperatures, gutters and downpipes are at risk of freezing and cracking. During winter months, check for ice buildup inside the downpipes, and consider insulating them to prevent damage from freezing.

Rainwater Tanks

• Interior Cleaning: To prevent the buildup of sediment, algae, or debris inside the tank, perform interior cleaning. If significant sludge accumulates, it may need to be removed manually or with a pump.
• Inlet Screen: The screen or filter at the top of the tank should be cleaned regularly to prevent large debris, such as leaves or twigs, from entering the tank. This is especially important after heavy storms or in areas with many trees.
• Overflow Pipe Check: Ensure that the overflow pipe is clear of blockages and directs water away from the tank’s foundation to avoid soil erosion or flooding.
• Inspecting for Leaks and Cracks: Regularly inspect the tank for leaks or cracks around seams, joints, and the base. Even small cracks can allow contaminants to enter or cause water loss. Seal any cracks or replace damaged parts to maintain the tank’s integrity.
• Foundation and Base: Check that the tank sits level on a stable surface. Shifting or settling can affect the tank’s performance and lead to potential damage. Clear the area around the tank’s base of debris, vegetation, or obstructions that could destabilize the tank.

Water Treatment Equipment

• Activated Carbon Filters (for water purification): inspect regularly for signs of exhaustion or contamination. Replace filters periodically (typically every 6 to 12 months, depending on usage). 

• Sediment Filters (which remove dirt, silt, and larger particles): inspect regularly and clean or replace every 3 to 6 months. 
• UV (ultraviolet) Water Treatment Systems (used to disinfect rainwater by killing bacteria, viruses, and other pathogens): Clean the lamp every 6 – 12 months and replace in accordance with manufacturer requirements. 
• Reverse Osmosis (RO) Systems (effective at removing impurities like salts, metals, and other contaminants): systems typically have multiple stages of filtration, each requiring periodic replacement depending on manufacturer’s guidelines.
• Chemical Treatment Equipment (such as chlorine or disinfectants), inspect the equipment regularly to ensure it’s dispensing the correct amount of chemicals. Check the chemical storage and dosing equipment for leaks, corrosion, or blockages. Replenish chemicals according to the system’s usage. Overuse or underuse can affect water quality.

Circulating Pumps 

• Refer to our previous article for a detailed description. 

Water Quality Testing

• Periodically flush the full system to ensure correct operation and test the quality of the treated water. Test for common contaminants such as bacteria, pH, heavy metals, and chlorine levels to ensure the treatment process is effective.

Industry Best Practices and Regulatory Standards

All maintenance should be performed in line with industry best practices and the latest regulatory requirements. Relevant standards for rainwater harvesting and treatment systems include:

• AS 3500:2021: Plumbing and Drainage
• BS EN 16941-1:2024: On-site non-potable water systems – Systems for the use of rainwater
• CSA B805:22/ICC 805:2022: Rainwater Harvesting Systems

Dewick & Associates’ in-house technical writing team is up-to-date with the latest legislation and can provide relevant advice on maintenance requirements. Additionally, Dewick & Associates offers detailed Operation and Maintenance (O&M) manuals, complete with step-by-step Preventative Maintenance Log Sheets for all equipment, which are used on-site throughout the building’s life cycle. These logs help ensure that the system is well-maintained, operating efficiently, and in compliance with regulations.

Regular and proper maintenance of rainwater recycling systems not only ensures longevity but also guarantees that the system continues to operate safely and efficiently, contributing to water conservation and cost savings.

Author: Louise Gardner, General Manager