Recirculating vs Run-to-Waste Hydroponic Systems

Tara | May 8, 2023
Plants in Space: Resources

Recirculating and Run-to-Waste systems are two popular types of hydroponic systems that are used to grow plants indoors. Both systems have their own advantages and disadvantages which should be considered when choosing the best system for a specific application.

Recirculating Hydroponic Systems

In recirculating hydroponic systems, nutrient-rich water is circulated through the system to provide the plants with the essential nutrients they need for growth. The water is then collected, filtered, and reused multiple times before being replaced with fresh nutrient solution. This type of system is highly efficient, as it conserves water and nutrients while minimizing waste.


  1. Water and nutrient conservation: Since the nutrient solution is reused, these systems are more environmentally friendly and cost-effective.
  2. Uniform nutrient distribution: Nutrient levels are consistent throughout the system, ensuring optimal plant growth.
  3. Easier to maintain and control: Recirculating systems allow for better control over pH, nutrient concentration, and other environmental factors.


  1. Higher initial cost: These systems require more equipment and infrastructure, leading to higher startup costs.
  2. Increased risk of disease: Reusing water can increase the risk of spreading pathogens or pests among plants.
  3. Need for constant monitoring: Recirculating systems require regular maintenance and monitoring to ensure optimal conditions.

Examples of Recirculating Hydroponic Systems:

  1. Nutrient Film Technique (NFT): In NFT systems, a thin film of nutrient solution constantly flows over the roots of plants, which are supported by sloping channels or trays. The excess nutrient solution is collected at the end of the channel and recirculated back to the reservoir. NFT is well-suited for growing small, fast-growing plants like lettuce and herbs.
  2. Aeroponics: Aeroponic systems utilize a nutrient mist that is sprayed directly onto the roots of the plants, which are suspended in air within a closed or semi-closed environment. The excess nutrient solution drains back into the reservoir and is recirculated. This method allows for excellent oxygenation of the roots and is suitable for a wide variety of plants.
  3. Deep Water Culture (DWC): In DWC systems, plant roots are submerged in a nutrient-rich water solution that is oxygenated with air stones or diffusers. The water in the DWC system is continuously recirculated, ensuring consistent nutrient levels. DWC is particularly effective for growing leafy greens and herbs.
Run-to-Waste Systems

Run-to-waste systems, also known as drain-to-waste systems, involve providing plants with a nutrient solution that is drained away after each use, instead of being recirculated. The excess solution, along with any unused nutrients, is discarded as waste. This prevents the buildup of salts and other unwanted elements in the growing medium, which can be harmful to the plants.


  1. Lower risk of disease: Since the nutrient solution is not reused, the risk of spreading pathogens or pests is reduced.
  2. Simpler setup: These systems typically require less equipment and infrastructure, resulting in lower initial costs.
  3. Easier nutrient management: The risk of nutrient imbalances is lower as fresh nutrient solution is used for each watering.


  1. Less water and nutrient efficient: Run-to-waste systems use more water and nutrients, as the excess solution is discarded.
  2. Environmental concerns: The discarded nutrient solution can potentially harm the environment if not properly disposed of.
  3. Inconsistent nutrient distribution: Nutrient levels can vary throughout the system, which may affect plant growth.

Examples of Run-to-Waste Hydroponic Systems:

  1. Drip Irrigation: In drip systems, nutrient solution is slowly dripped onto the base of each plant, either directly into the growing medium or through emitters. The excess solution drains out of the growing medium and is discarded. Drip irrigation is versatile and can be used for a wide range of plants, including vegetables, fruits, and flowers.
  2. Ebb and Flow (Flood and Drain): Ebb and Flow systems involve periodically flooding a grow tray with nutrient solution, which then drains back into a reservoir. In a run-to-waste setup, the drained solution is not recirculated and is replaced with fresh nutrient solution for each flooding cycle. Ebb and Flow systems are suitable for a variety of plants, particularly those with high water requirements.
  3. Hand Watering: Hand watering is a simple run-to-waste method in which plants are grown in containers filled with a growing medium (such as coco coir, perlite, or vermiculite) and watered manually with a nutrient solution. The excess solution drains out of the containers and is discarded. This method is labor-intensive but allows for greater control over watering frequency and nutrient levels.

To sum up, recirculating hydroponic systems are more water and nutrient-efficient, making them an environmentally friendly and cost-effective option. However, they require more maintenance and have a higher risk of disease. On the other hand, run-to-waste systems are simpler and have a lower risk of disease, but use more water and nutrients and may have environmental concerns. The choice between the two systems depends on individual preferences, resources, and specific growing conditions.

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