Read time: 7 minutes
Quick answer: A rainwater harvesting installation involves choosing a tank location, excavating, placing the underground tank, fitting the filter and connecting the downpipes, then backfilling in layers whilst raising the water level inside the tank. Finally, you connect the tank to the house, set up the pump package and mark all rainwater pipework.
Rainwater is often underestimated, but it can make a real difference to your home. A GRAF UK rainwater harvesting system can reduce your home’s demand for precious drinking water by up to 50%, whilst championing environmental conservation. GRAF systems combine intelligent components with a modular design for effortless integration. This guide takes you through each stage of a rainwater harvesting installation so you can make the most of free rainwater.
Where should you position an underground rainwater tank?
Where you place your tank is one of the most important decisions in a rainwater harvesting installation. The location you choose can significantly affect both the efficiency and the look of your system.
For an ideal setup, position your tank 2 to 10 metres from your home. This strikes a balance. It is close enough to minimise piping and installation complexity, yet far enough away to avoid interfering with your daily activities.
Can you install a rainwater tank under a patio or driveway?
Yes. GRAF UK offers smart solutions for installing your tank under a patio or driveway, ensuring both convenience and safety. This means your rainwater harvesting installation can make the most of the space available without sacrificing the look of your outdoor area.
How do you excavate for a rainwater harvesting installation?
Careful planning is essential before you pick up a shovel. Pay close attention to any guidelines on slopes and groundwater levels in your region. Understanding these factors ensures your tank is properly placed for efficient water collection.
Once you’ve chosen the area and removed potential obstacles such as roots or rocks, it’s time to dig. The excavation should match your tank’s specifications and dimensions. The depth should allow the tank to be fully buried whilst maintaining proper clearance for connections.
How do you place the tank and attach the turret?
GRAF tanks are designed to be user-friendly as well as efficient. They are surprisingly lightweight, which eliminates the need for heavy machinery during installation. A small team or even a few capable individuals can handle them easily.
Gently lower the tank into the excavated trench, paying close attention to its alignment. Make sure it sits horizontally and securely within the excavation. Proper alignment ensures efficient water collection and prevents future complications. Double-check that the inlet and outlet connections are in the right positions.
Next, locate the designated opening or access point on the top of the tank. This is where the tank turret attaches. Carefully fit the turret to the opening, ensuring a snug and watertight fit.
How do you install the filter package and connect the downpipes?
The next stage of your rainwater harvesting installation is setting up the filter package and connecting the roof downpipes. Both are integral to collecting rainwater efficiently whilst maintaining the integrity of the system.
Start by installing the filter package. It plays a key role in filtering out debris and contaminants from the rainwater before it enters your tank. [Internal link: rainwater harvesting filters]
Next, connect your roof downpipes to the system. The downpipes channel rainwater from your roof to the filter package and, ultimately, into the tank. Use appropriate fittings and connectors to make a secure connection.
As you go, incorporate the overflow u-bend. This component manages excess rainwater and prevents overflows. Make sure the u-bend has a minimum decline of at least 1% in the same direction as the flow, to support efficient water management.
How do you backfill around an underground rainwater tank?
Backfilling fills the excavated space around your tank to secure it and create a stable foundation. Done properly, it keeps your rainwater harvesting installation reliable and efficient for years to come. A GRAF system doesn’t require concrete for backfilling, which makes the installation process more eco-friendly and straightforward.
Choose gravel or a similar backfill material that provides adequate drainage and support. Using appropriate materials is essential for maintaining the integrity of your underground tank and preventing soil erosion.
Add the backfill material in layers of approximately 30cm at a time. Layering helps distribute the weight evenly and minimises the risk of settling or uneven ground.
As you add each layer, raise the water level inside the tank at the same time. This counteracts the pressure from the backfill material and helps maintain the tank’s stability.
After each layer, use a suitable compaction method so the material settles evenly around the tank. Adequate compaction prevents voids and ensures a solid foundation.
Fit the dome shaft before backfilling is complete, while the hole is still partially filled. With GRAF, you can place the dome shaft so it sits flush with the ground, giving a neat, seamless finish within your landscape. The dome shaft is the access point for maintenance and monitoring of your system. Its user-friendly design makes it easy to open and close as needed, keeping your system efficient and trouble-free.
How do you connect the rainwater tank to your home?
This is the stage where harvested rainwater is brought into your home. You connect the underground tank to your house using a pipe, and the control panel inside your property manages the entire operation.
Connect one end of the pipe to the outlet or distribution point of your tank. Make sure the connection is secure and watertight to prevent any leaks or disruptions in the rainwater transfer. Then carefully route the other end to your home, following the path or conduit established during the planning phase of your rainwater harvesting installation. Make sure the pipe is properly supported and protected along its route to prevent damage.
Which pump package does your rainwater harvesting installation need?
The pump package lets you manage and monitor the entire system efficiently, and the type you choose dictates how you set it up. [Internal link: rainwater harvesting pumps]
If your system has a submersible pump inside the underground tank, you need to feed a power supply through the ducting from the home to the tank. If you choose an external wall-mounted pump, you only need to feed a power supply to the unit. The unit can be housed in a garage, basement or plant room.
Why do rainwater pipes need to be marked?
The final step of your rainwater harvesting installation is making sure all rainwater pipes are appropriately marked, to distinguish them from pipes used for drinking water. This simple but important step prevents confusion. It also guarantees that harvested rainwater is used for its intended purposes and preserves the quality of your potable water supply.
As part of UK water regulations, rainwater pipes are distinctly colour-coded in black and green. This avoids the possibility of rainwater being used where potable tap water is needed.
Is a rainwater harvesting installation right for your home?
GRAF UK rainwater harvesting systems are designed with both your convenience and environmental responsibility in mind. With the potential to reduce your home’s demand for precious drinking water by up to 50%, a GRAF system is a sustainable choice that benefits both you and the planet.
To find the right tank for your home, try our tank size calculator. If you need any assistance with the installation of your rainwater harvesting system, don’t hesitate to contact us. Our team of friendly experts are always happy to help.
Posted by Catherine Wainwright, on November 3, 2023.