What does a rainwater harvesting diagram show?
A rainwater harvesting diagram is a visual representation showing how water flows from the moment it falls on the roof through to its delivery to points of use. These diagrams are valuable educational tools that help homeowners understand system components and how they connect.
Basic Components Shown in a Diagram
A typical diagram starts with the roof as the catchment surface, showing arrows representing rainfall. Gutters along the roof edge collect water and direct it to downpipes. A downpipe diverter or filter is shown where the downpipe meets the storage tank, with an arrow showing filtered water entering the tank and debris being directed to waste. The storage tank is depicted as the central element, usually cut away to show internal components. An overflow pipe exits near the top of the tank, directing excess water away from the building.
Internal Tank Details
Many diagrams show the inside of the storage tank. A floating intake filter draws water from just below the surface, avoiding sediment at the bottom. The pump is shown either submerged (submersible) or external. A float switch or level sensor monitors water level. The incoming pipe from the diverter is shown entering through the top or side. The outlet pipe to the distribution system exits from the pump. The overflow pipe is positioned below the inlet to prevent backflow.
Distribution System
After the pump, the diagram shows the pipework dividing into separate lines for different uses. One line may go to garden taps, another to the toilet cistern, and another to the washing machine. Each distribution point is labelled. In systems with mains backup, a float valve or automatic valve is shown connecting to the mains supply. Non-return valves are indicated on each supply line to prevent backflow. Filters and UV disinfection units are shown on the distribution side for indoor systems.
Electrical and Control Elements
More detailed diagrams include electrical components. The control panel is shown connected to the pump, float switch, and mains backup valve. A weatherproof electrical supply is indicated. Some diagrams show a rainwater gauge or smart monitoring system with a wireless connection to display the water level on a mobile phone. The diagram may also show frost protection for external pipework and a drain valve for winter maintenance.
Labels and Annotations in Diagrams
A good rainwater harvesting diagram includes clear labels for each component. The catchment surface is labelled with the roof material and area. Gutters and downpipes are labelled with their sizes and materials. The leaf filter or downpipe filter is shown with an arrow indicating the direction of debris flow to waste. The storage tank is labelled with its capacity and material. The overflow pipe is shown with a note indicating its destination — typically a drain, soakaway, or rain garden. The pump is labelled with its type and specifications. Each distribution pipe is labelled with its use: garden tap, toilet supply, washing machine supply. Pipes carrying non-potable water are marked with the standard warning label or colour coding. Mains backup connections include a note about the required air gap or non-return valve for backflow prevention.
Creating Your Own Diagram
Creating a diagram of your own rainwater harvesting system is a valuable exercise that helps with planning, installation, and future maintenance. Start by sketching your roof layout and identifying all downpipe positions. Mark the location where your tank will be placed and draw the pipe routes from downpipes to the tank. Include all fittings, valves, and connections. Add the pump location and the distribution pipework to each point of use. Show the electrical supply for the pump and any control systems. Note the positions of isolation valves, drain valves, and access points for maintenance. Keep the diagram in a safe place for future reference — it will be invaluable when troubleshooting problems, planning upgrades, or explaining the system to new owners if you sell your property.