In the realm of rainwater harvesting, the type of pump you choose plays a pivotal role in ensuring efficient water distribution for various purposes. Cistern pumps, specifically designed for rainwater storage systems, come in different types, each catering to specific needs. Let's explore the various types of cistern pumps and their applications to help you make an informed decision.
Submersible Pumps: Submersible cistern pumps are installed inside the rainwater storage tank, submerged in the collected water. These pumps are quiet, efficient, and space-saving as they eliminate the need for a separate pump house. Submersible pumps are ideal for deep cisterns and are commonly used in residential rainwater harvesting systems.
Jet Pumps: Jet pumps are positioned above the water level and draw water from the cistern through a suction pipe. They are versatile and suitable for shallow to moderately deep cisterns. Jet pumps come in two types: shallow well jet pumps for shorter suction lifts and deep well jet pumps for deeper cisterns. These pumps are relatively easy to install and maintain.
Centrifugal Pumps: Centrifugal cistern pumps use a spinning impeller to create a flow of water. These pumps are efficient for moderate to high flow rates and are suitable for a wide range of applications, including irrigation and industrial use. Centrifugal pumps are often used in larger rainwater harvesting systems where substantial water distribution is required.
Diaphragm Pumps: Diaphragm cistern pumps operate by flexing a diaphragm to create a vacuum, drawing water into the pump chamber. These pumps are self-priming and can handle a range of water viscosities. Diaphragm pumps are commonly used in smaller residential rainwater harvesting systems for tasks like garden irrigation and toilet flushing.
Hand Pumps: For off-grid or emergency scenarios, hand pumps can be installed on cisterns to manually extract water. These pumps are simple, reliable, and do not require electricity. While not as common in everyday use, hand pumps provide a backup solution for times when power is unavailable.
Solar-Powered Pumps: In line with the growing trend of sustainable practices, solar-powered cistern pumps harness energy from the sun to operate. These pumps are eco-friendly, energy-efficient, and suitable for remote locations where access to electricity is limited. Solar-powered pumps are gaining popularity for their environmental benefits.
To select the proper pump for rainwater harvesting. You will need have a basic understanding of your water needs and usage. You can do this by creating a chart to help determine your total dynamic head.
Creating a chart for determining total dynamic head (TDH) for typical water demands of a residence involves considering various factors such as the flow rate, pipe size, elevation changes, friction losses, and pressure requirements. Here's a simplified example of how such a chart might look:
GPM | Pipe sz in | Elevation ft | Friction Loss | PSI | TDH |
5 | 0.5 | 10 | 5 | 40 | sum |
10 | 0.75 | 15 | 7 | 45 | sum |
15 | 1 | 20 | 10 | 50 | sum |
20 | 1.25 | 25 | 12 | 55 | sum |
25 | 1.50 | 30 | 15 | 60 | sum |
In this chart:
Flow Rate (GPM): Typical water demand in gallons per minute.
Pipe Size (inches): Diameter of the pipe used for water distribution.
Elevation Change (feet): Difference in elevation between the water source and the highest point of use.
Friction Losses (feet): Losses due to friction as water flows through the pipe.
Pressure Requirements (PSI): Desired pressure at the highest point of use.
Total Dynamic Head (feet): Calculated sum of elevation change, friction losses, and pressure requirements. This is the TDH that the pump needs to overcome to meet the water demands of the residence.
This chart provides a starting point for estimating the TDH for typical water demands of a residence. However, it's important to note that actual values may vary depending on specific system characteristics and local conditions. Detailed calculations and considerations may be necessary for accurate design and sizing of water distribution systems.
Selecting the right cistern pump is essential for optimizing the performance of your rainwater harvesting system. Consider factors such as cistern depth, water usage, and power availability when making your decision. Whether you opt for a submersible, jet, centrifugal, diaphragm, hand, or solar-powered pump, each type brings its own set of advantages to the table. By choosing the most suitable cistern pump for your needs, you can maximize the benefits of rainwater harvesting while promoting sustainability. Contact Olympic and we can help size a pump for you based on your water needs.
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