Water Harvesting Pits: An Innovative Way to Capture and Conserve Water

Water harvesting is the process of collecting, storing and utilizing rainwater or surface runoff for productive purposes such as agriculture, domestic use and groundwater recharge. It is an ancient, sustainable method to manage water resources, particularly in regions facing water scarcity or irregular rainfall.

Water harvesting pits are among the technologies used in water harvesting. They are a simple, cost-effective method of capturing and storing rainwater.

Benefits of Water Harvesting Pits:

1. To capture rainwater and allow it to infiltrate into the ground.
2. To prevent soil erosion and reduce the risk of flooding.
3. To supplement water supply for agricultural, domestic or industrial purposes.
4. To improve soil moisture and support vegetation growth.
5. To save cost on external water supply systems.
6. To ensure water availability for communities in arid and semi-arid regions.

Types of Water Harvesting Pits:

1. Shower Pits: They are systems designed to collect and reuse water drained from showers. The collected water is not used for drinking but for purposes such as irrigation, flushing toilets or groundwater recharge.
2. Orchard Pits: They are small to medium-sized depressions or trenches dug around or near trees to capture rainwater and surface runoff.
3. Recharge Pits: These are shallow excavations filled with permeable materials like gravel or sand to allow water to sink into the groundwater.
4. Storage Pits: These pits store water for direct use, often lined with clay or plastic to minimize seepage.
5. Contour Trenches: Long, shallow pits aligned along the land contours to capture runoff and allow water to sink into the ground slowly.

Design Considerations:

1. Size and Depth: Depends on the volume of rainfall, soil type and water demand.
2. Location: Must be placed in areas with high runoff or where groundwater recharge is needed.
3. Material: Gravel, sand and porous stones for recharge pits; clay or liners for storage pits.

Steps for Construction:

1. Site Selection: Choose a low-lying area with good soil permeability.
2. Excavation: Dig the pit to the required dimensions.
3. Lining (if needed): For storage pits, line with clay or a waterproof material.
4. Filling: Add layers of coarse gravel, sand, and fine aggregates for recharge pits.
5. Maintenance: Regularly clean the pit and remove accumulated debris or silt.

Read more on water harvesting from the link below:

Author: Rabecca Mwila

PELUM Zambia Communications Officer-KHSA Project