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Water Recycling System
Updated September 22, 2025
Greywater system
A greywater system collects gently used water from sinks, showers, and laundry. It then recycles that water for uses like landscape irrigation.
Category
Water Recycling System
Use Case
Reusing household wastewater from sinks, showers, and laundry for irrigation or toilet flushing
Key Features
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Water Reuse From Household Sources
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Reduction In Fresh Water Consumption
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Simple Filtration And Treatment Process
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Safe Irrigation For Non-Edible Plants
In Simple Terms
What It Is
A greywater system is a way to reuse water that has already been used once in your home, but isn't heavily soiled with things like human waste. Think of it as giving water a second job. This water comes from places like your shower, bathtub, bathroom sink, and washing machine. It's called 'greywater' because it's not perfectly clean like fresh tap water, but it's also not as dirty as the water from your toilet, which is called 'blackwater' and needs to go to the sewer.
Why People Use It
People install greywater systems for two main reasons: to save money and to help the environment. By reusing water, you significantly cut down on your water bill because you're not using as much fresh water from the tap for things like watering plants. It also reduces the strain on your local community's water supply and wastewater treatment systems. In simple terms, you're recycling water at home, which is a smart and eco-friendly thing to do, especially in areas that experience droughts or have high water costs.
Everyday Examples
The most common and simple use for a greywater system is watering your lawn, garden, or trees. For instance, instead of letting all the water from your washing machine or shower just go down the drain, a basic system can divert it through a hose to your yard. A more advanced setup might filter the water and send it through a separate set of underground pipes with drip irrigation to directly water the roots of your plants. It's important to only use biodegradable soaps and detergents to keep your soil healthy. You wouldn't use this water for drinking or for spraying on vegetable gardens you plan to eat from raw, but it's perfectly good for keeping your ornamental plants alive and green.
Technical Details
Definition
A greywater system is a water recycling setup that collects, treats, and reuses gently used water from household sources like showers, baths, bathroom sinks, and laundry. It excludes water contaminated with fecal matter, which is classified as blackwater and requires separate handling. The primary purpose of a greywater system is to reduce freshwater consumption and lessen the burden on municipal sewage systems or septic tanks by repurposing water for secondary, non-potable applications.
How It Works
Greywater is diverted from source fixtures through a separate plumbing network that avoids cross-connection with the potable water supply. This water is then directed to a filtration unit to remove solids, hair, and lint. Depending on the system's complexity, it may undergo further treatment such as sedimentation, biological processing, or disinfection. Once treated to the required standard, the water is stored in a dedicated tank and then distributed via a pump or gravity feed to points of use, such as irrigation systems or toilet flushing. Systems are designed to ensure that greywater is used promptly to prevent stagnation and bacterial growth.
Key Components
Collection Plumbing: Separate pipes that gather greywater from source fixtures.
Filter or Screen: Removes large particulates and debris to prevent clogging.
Surge Tank: A vessel that holds greywater briefly before it enters the treatment process.
Treatment Unit: Varies from simple sand filters to more advanced membrane bioreactors for purification.
Storage Tank: Holds treated greywater until it is needed for reuse.
Distribution System: A pump and separate piping network that delivers the water to its end use.
Overflow and Bypass: Safely directs excess greywater to the sewer or septic system if the storage tank is full.
Common Use Cases
Subsurface Irrigation: Watering non-edible plants, lawns, and trees via drip lines or soaker hoses that minimize human contact.
Toilet Flushing: Diverting treated greywater to supply water for flushing toilets, significantly reducing indoor potable water use.
Outdoor Cleaning: Using recycled water for washing vehicles, patios, or other outdoor surfaces.
* Ornamental Water Features: Supplying water for fountains or ponds where human ingestion is not a risk.
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