DWC: Recirculating vs Drain To Waste

DWC has been one of the most popular hydroponic systems in the market. There are different forms and designs for a DWC system like the recirculating and the drain to waste system. It got me to wonder, what is the difference between a recirculating and a drain to waste DWC system?

The recirculating vs drain to waste system, what is the difference between them? There is a huge difference between both systems. A recirculating system can be better for large scale hydroponic farms where several plants are grown together. On the other hand, the drain to waste system can be more suitable for growing hydroponic plants on a small scale.

Both systems are great and can be used to grow thriving hydroponic crops. The real question is which system is the most suitable for your situation. But to answer such a question, you need to first know how both systems work.

In this article, I will explain exactly how to choose the right system to grow hydroponic plants that can thrive for years to follow.

What Is The Difference Between A Recirculating System And Drain To Waste System?

The recirculating system and drain to waste system are somehow related to each other except for a single major aspect, which is how will the nutrient solution runoff be expelled.

What Is A Recirculating System?

One of the main features of a recirculating DWC is that the entire system of units is connected together through pipes to the main nutrient reservoir. The runoff nutrient solution will pass through connected tubes from the DWC system to reach the nutrient reservoir.

The nutrient reservoir collects and mixes the solutions of the entire hydroponic DWC recirculating systems together. When it reaches the nutrient reservoir, the pH and nutrient ppm will then be tested again and get set back to the normal levels. Moreover, any decrease in the water level will be topped off again.

What Is A Drain To Waste System?

On the other hand, in a drain to waste system, the runoff nutrient solution will be expelled by simply draining it. No recycling will be done.

Checkups on the nutrient solution will be done regularly, and flushing must be done in time to ensure that there is no build-up of salts.

The Advantages And Disadvantages Of A Recirculating System


1-Recycling Water

Decreasing the water consumption is one of the most critical benefits of using hydroponic systems. In fact, hydroponics can save up to 80% of the consumed water when compared to soil.

When using a recirculating system, you are saving a considerable amount of water that would be otherwise drained away every time you flush your system. This can significantly decrease your monthly water utility bills and if you are using hydroponics systems on a large scale, you can save a huge amount of monthly expenses.

2-Reduce Nutrient Consumption

Nutrients are added every now and then to the nutrient reservoir whenever the ppm falls below certain levels. The nutrient ppm levels must be kept stable most of the times to ensure a healthy growth rate for the crops.

The recirculating system tend to save a lot of nutrients from draining to waste. Instead of flushing your hydroponic system and wasting a great amount nutrients, you are recycling the already existing nutrients in the nutrient solution.

3-Can Be Used On Large Scale

In my opinion, using hydroponic systems on a large scale is the key to make hydroponic farms as profitable as growing in soil. Having all of your DWC systems connected together through pipes to a large central nutrient reservoir will save you a lot of work and energy.

Imagine having to test the ppm and pH of 50 nutrient solution reservoirs everyday, pretty exhausting job right? Well, you don’t have to deal with all of these reservoirs if you are using a recirculating system. You will simply have to monitor one central reservoir everyday, that’s it.


1-Clogged Pipes

By using a recirculating system with its complicated pipe network, you will have an increased chance of getting these pipes clogged due to various reasons.

These pipes might get clogged due to several reasons like the growth of algae and bacterial biofilms. Moreover, the accumulation of dead plant roots might also raise the chances of your pipes getting clogged.

2-The Spread Of Water Borne Disease Easily

There is a huge disadvantage of having all of your plants connected together to a single nutrient reservoir which is the easy transmission of waterborne disease.

When a single plant gets infected with a certain disease in a normal drain to waste the DWC system, it can be isolated from other surrounding plants to decrease the risk of spreading the infection. Unfortunately, this cannot be done in a recirculating DWC system.

You have to understand that there is an associated risk of rapid disease transmission once you have chosen to use the recirculating system as your main DWC growing method. You can reduce the risk of getting your whole hydroponic crop infected by separating them into different recirculating systems with several nutrient reservoirs.

3- Growing A Limited Variety Of Plants

Different plants do require different ppm and pH levels in order to thrive. This was previously done easily when the drain to waste system was being used, but now by using a recirculating system, it has become more difficult to do so.

If you chose to use the recirculating method, you will have to grow plants with similar ppm and pH requirements together in the same system. Growing different varieties of plants will require more than one recirculating system for every plant species to thrive.

The Advantages And Disadvantages Of A Drain To Waste System


1-Less Transmission Of Water Borne Disease

One of the perks of having a drain to waste DWC system is that the nutrient solution is not connected with other systems.

By having a drain to waste system, each DWC system will be separated from other systems inside the same grow room; this will limit the spread of any waterborne disease that might get transmitted through the nutrient solution to reach the other plants that you are trying to grow.

2-Less Salt Accumulation

The drain to waste method depends heavily on draining the entire nutrient solution every time we are flushing the system. This process significantly reduce the risk of accumulating salts. High concentration of salts can result in a nutrient lockout which can severely harm your hydroponics plants.

3-Better Pest Control Measures

Imagine having a pest infestation in a plant inside a recirculating DWC system. It would be a nightmare for you to figure out how to use pest control chemicals inside the nutrient solution without allowing other plants in the same system to absorb it.

This is not the case anymore with the drain to the waste system. Having the nutrient solution of every DWC system separated will provide you with the great advantage of limiting the use of pest control chemicals to the only infected plants.

4-Lower Probability Of Clogging The System

Another perk of using the drain to waste method is that there are no pipes or emitters involved in the system; this will most probably save you a lot of headaches because pipes tend to clog frequently in systems using the recirculating method.


1-Increased Water Consumption

By draining the whole nutrient solution every time you flush the system, there will be a huge amount of water wasted monthly. Water efficiency is one of the most significant perks in hydroponics and losing it will make me doubt the viability of hydroponics over the soil again.

2-Waste Of Nutrients

Unfortunately, the drain to waste system tend to waste a lot of nutrients whenever there is a flush to be done. These nutrient costs will add up every month to your expenses, and if you are growing hydroponics on a large scale, it can severely decrease your profit margin.

2 thoughts on “DWC: Recirculating vs Drain To Waste

  1. If I’m running 8 plants, how many gallons per hr. And how big of a reservoir should I have? And how thick should the tubing/piping be…? Basically I bought a DWC kit, thinking it was an RDWC kit, but found a pump that can do like 1000 gallons per hr for like $25 + 50 gallon not clear plastic tote, that I think I might keep just outside of my tent, to help keep water temps down. Do you think a 50 gallon reservoir is enough for 8 plants, and do you think the pump will be sufficient? And what size tubing would you use for ‘daisy chain’ or linking them up? Please let me know what you think… any and all advice is welcomed… I’m newer to this.

  2. I wonder if you can recycle the nutrients.
    For instance: use them in non-hydroponic plants/vegetables.
    Perhaps give filtered and in lower quantities to plants.
    Just wondering.

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