How to install a rainwater harvesting system

Installing a rainwater harvesting system doesn’t have to be a daunting task. In this blog, we’ve broken down the steps for you, making it straightforward to start collecting rainwater as soon as possible.

What is a Rainwater Harvesting System and How Does It Work?

A rainwater harvesting system is a sustainable solution designed to capture, store, and reuse rainwater that would otherwise be lost to runoff. The process begins with the collection of rainwater from rooftops, which is then channelled through downpipes into a storage tank. Before the water reaches the tank, it passes through a filter to remove debris and contaminants. Once stored, this non-potable water can be repurposed for various uses, such as garden irrigation, flushing toilets, and washing clothes, significantly reducing the demand for treated mains water.

Types of Rainwater Harvesting Systems

Rainwater harvesting systems vary by complexity, usage, and installation type. Here’s a look at the primary categories:

• Garden-Only Systems: These are the simplest types of systems, designed specifically for garden irrigation. They often consist of a basic setup where collected rainwater is stored in barrels or simple tanks and used exclusively for watering gardens.
• Pumped Systems: These systems pump water directly from the storage tank to the points of use as needed. They are efficient and ensure that water is available on demand, but they require reliable pump technology.
• Gravity-fed Systems: Gravity-fed or indirect systems first pump the water to an elevated header tank. From this tank, water is distributed by gravity. This setup is often used in larger buildings or when consistent water pressure is needed throughout.

Main Components of a Standard Rainwater Harvesting System

Regardless of the type, all rainwater harvesting systems include several key components:

• Storage Tank: This is where the clean rainwater is held until needed.
• Filter: Filters clean the water before it enters the storage tank to prevent clogging and maintain water quality.
• Pump: Depending on the system type (gravity-fed or pumped), the pump plays a crucial role in distributing the water.
• Lid: A secure lid is essential for maintaining water quality by preventing debris and contaminants from entering the storage tank.

Pre-Installation Planning

Before diving into the installation of a rainwater harvesting system, careful planning is essential to ensuring the success and legality of your project. Here’s how to effectively prepare:

Assessing the Suitability of Your Property

• Roof Type and Condition: Check if your roof is suitable for collecting quality rainwater. Ideal roofing materials include metal, slate, or tiles. Avoid roofs with toxic materials or heavy wear.
• Catchment Area: Evaluate the size of your roof to estimate the amount of rainwater that can be collected. Larger roof areas can collect more water, enhancing the amount of rainwater that can be used.
• Space for the Tank: Ensure there is adequate space on your property for the storage tank. Consider both surface and underground options, depending on your property’s layout.
• Surrounding Environment: Check for potential contaminants like overhanging trees or exposure to high levels of pollutants, which might affect the water quality.

Necessary Tools and Materials for the Installation

• Measuring Tools: Tape measure, level, and plumb line for accurate placement and levelling.
• Digging Equipment: Shovel or backhoe for excavating the site for underground tanks.
• Gravel: A layer of compacted, round-grained gravel (grain size 10/20, thickness approx. 100 – 150mm) is necessary for the proper foundation and backfill around the tank.
• Plumbing Supplies: pipes, fittings, sealants, and PVC cement for secure connections.
• Safety Gear: gloves, goggles, and protective clothing to ensure safety during the installation.

Legal and Safety Considerations

• Building Codes and Permits: Check with your local government or planning agency to find out about necessary permits and building codes related to water harvesting systems. This may include specific requirements for tank placement, plumbing modifications, and runoff management.
• Environmental Regulations: Some regions have regulations regarding the redirection of rainwater runoff, especially if it affects storm drains. Ensure compliance with these regulations to avoid legal issues.
• Health and Safety Standards: Follow best practices for installation to avoid any structural damage or personal injury. This includes securing tanks to prevent tipping and ensuring all electrical installations, if any, comply with safety standards.

Installation Steps

Excavation

Guidelines for Excavation: Determine the appropriate depth and location for your underground tank, considering the local soil conditions, frost line, and groundwater levels. The trench should be deep enough to accommodate the tank and allow for at least 100 – 150mm of gravel base and sufficient coverage above the tank.

Considerations for Slopes and Groundwater Levels: Avoid areas with high groundwater levels to prevent the tank from “floating.” If installing on a slope, ensure proper drainage and stability to prevent shifting.

Tank Installation

Placing the Tank Horizontally: Lower the tank carefully into the trench, ensuring it sits level on the gravel base. This alignment is crucial for the proper functioning of the inlet and outlet pipes.

Connecting the Tank Turret: Attach the turret to the tank, ensuring a secure and watertight seal. This component is critical as it interfaces with surface level and must withstand environmental exposure.

System Components Setup

Installing the Filter Package: Set up the filtration system to ensure that only clean water enters the storage tank, extending the lifespan of the system and reducing maintenance needs.

Connecting Downpipes and the Overflow U-Bend: Attach the downpipes from the roof gutters to the tank’s inlet, using the overflow u-bend to prevent overflow and direct excess water away safely.

Ensuring Proper Incline for Effective Flow: Ensure that all pipes have a minimum decline of at least 1% towards the tank to facilitate water flow by gravity.

Backfilling

Techniques for Backfilling: Use round-grained gravel to fill around the tank, compacting it in layers of about 30cm. This method helps support the tank and prevents pressure points that could cause damage. Simultaneously raise the water level in the tank to balance the pressure from the backfill.

Dome Shaft and Control Panel Installation

Adjusting the Dome Shaft to Ground Level: Install the dome shaft, adjusting it to ensure it is flush with the ground level, facilitating easy access for maintenance without being obtrusive.

Installing and Configuring the Control Panel: Set up the control panel in a location such as the garage or utility room. Ensure it is easily accessible for monitoring and adjusting the system settings.

Final Connections

Connecting the System to Usage Points: Depending on your specific setup (garden-only or whole property system):

Garden-Only Systems: Route the pipes directly from the tank to garden taps or irrigation systems. Use manual or automated valves to control the flow.

Whole Property Systems: Establish plumbing connections from the tank to various non-potable water fixtures inside the property, such as toilets and washing machines. Ensure that these systems are separated from potable water supplies.

Labelling Rainwater Pipes: Clearly label all rainwater pipes to differentiate them from those carrying potable water. This is crucial to ensure there is no cross-contamination and to comply with local plumbing codes.

Post-Installation

After installing your rainwater harvesting system, it’s important to ensure that it operates efficiently and effectively. Here are essential steps and tips for testing, maintaining, and troubleshooting your system:

Testing the System to Ensure Functionality

Initial Inspection: Check all connections for leaks. Ensure that seals are tight and that there is no water escaping from the connections or the tank itself.

Test Run: Run water through the system to ensure that it flows correctly from the collection area through the pipes, filters, and into the tank. Verify that the pump and control panel are functioning as expected.

Quality Check: Inspect the quality of the filtered water to ensure it’s free from debris and contaminants. This might include visual checks or using a simple water testing kit.

System Monitoring: Monitor the system during a rainfall to ensure that water is correctly diverted into the tank and that overflow systems engage properly when the tank is full.

Maintenance Tips to Keep the System Running Efficiently

Regular Cleaning: Clean the roof catchment area, gutters, and downpipes regularly to prevent blockages and ensure maximum water collection. The frequency of cleaning depends on your environment, but typically before and after rainy seasons.

Filter Maintenance: Check and clean the filters regularly according to the manufacturer’s guidelines to prevent clogs and maintain water quality.

Tank Inspection: Inspect the tank annually for any sediment build-up or residue and clean it as necessary to maintain the storage capacity and water quality.

Pump and Control Panel Care: Service the pump and check the control panel periodically to ensure they are working efficiently. This includes checking for wear and tear on the pump and ensuring that all electrical connections are secure.

Installing a rainwater harvesting system is a proactive step towards sustainability, offering both environmental benefits and cost savings. If you have any questions on how to install your rainwater harvesting system, get in touch with our team of experts today, who are on hand to help you throughout the whole process.