Home Greywater Systems - Benefits and Potential Challenges

By: TomJuly 15, 2024

What is Greywater?

Not all concepts are black or white. Sometimes, the answer lies somewhere in between, otherwise known as a gray area. Greywater quite literally takes its name from the cloudy, sometimes grayish appearance it takes on after household or commercial usage. But, the definition also applies figuratively as well. Unlike potable white water, greywater is not pure enough for human consumption. But, it also does not present the same health risks as black water dispersed from the toilet, dishwasher or kitchen sinks. From an environmental standpoint, It’s that gray area that offers the greatest environmental benefits. Read on and find out why...

What is the Difference Between Grey, White & Black Water?

White Water

White (potable) water is water that is deemed safe for human consumption.
Ideal Usage of White Water:
  • Drinking & Food Preparation
  • Showering, & brushing teeth
  • Washing Laundry & Dishes

Greywater

Greywater, while not safe for consumption, can be reused for irrigation and flushing toilets. 
Ideal Usage of Grey Water:
  • Irrigation of Lawns & Gardens 
  • Flushing Toilets
  • Washing Laundry 

Black Water

Contains high levels of dangerous organic compounds. Must be sent to waste treatment center.
Sources of Black Water:
  • Bathroom Toilet
  • Dishwashing Machines
  • Kitchen Sinks

What is a Greywater System?

Simply put, a greywater system utilizes wastewater that can be repurposed for other uses. This includes water that has previously been used for washing clothing, showers, baths. or non kitchen water basins. It does not however, use waste water from toilets, dishwashers or kitchen sinks due to high bacteria levels. While greywater is not safe for consumption, greywater systems repurpose this water that would otherwise be sent directly to the local water treatment plant or your septic tank. Instead Greywater systems reuse greywater to irrigate lawns and gardens or flush your toilets. 

Types of Household Greywater Systems for Homes

Laundry to landscape, simple and complex are the three basic types of home greywater systems. These methods vary in sophistication, efficiency and cost. Yet, each has positive environmental benefits. 

Laundry-to-Landscape System

laundry to landscape system
Washing machines account for approximately 25% of all household waste water. Greywater from your washing machine is typically sent to a sewage plant for processing. Laundry-to-landscape systems divert this water to an irrigation system for your lawn and garden. This preserves valuable potable water that would normally be used for this purpose. Many communities prohibit watering your lawn during periods of drought. Laundry to landscape systems allows homeowners to maintain their grounds in times of hot, dry weather when fresh water supplies are limited. 

Cost of Laundry-to-Landscape System

Laundry-to-landscape is the simplest and most affordable way to utilize a greywater system. Professional installation can cost between $1,000 - $2,000 and take approximately 4 - 6 hours to complete. It’s important to note that the majority of this expense is attributed to the cost of labor. Ambitious DIY enthusiasts can save a considerable amount of cash by doing the job themselves
*More information on laundry-to-landscape DIY instructions

Are Permits Required for Laundry-to-Landscape Systems?

No, laundry to landscape does not require a building permit as long as this system does not alter any household plumbing. This is true because this type of system does not need electricity or switches to operate. Exemption from permits stipulates that greywater flow occurs by usage of the washing machine's existing pump and gravity only. 

Simple & Complex Greywater Systems

simple greywater system graphic
Simple and complex greywater systems utilize greywater diverted from bathroom sinks, showers, and bathtubs. Unlike laundry to landscape, simple and complex gray water systems require alterations to your home's plumbing. This may include the addition of surge tanks, pumps or filtration systems. What distinguishes simple from complex systems is the amount of greywater they disperse. Simple greywater systems divert under 250 gallons of gray water a day, Complex greywater systems divert over 250 gallons a day.

Cost of Simple & Complex Home Greywater Systems

The average cost of a simple greywater system is estimated at $,,000 - $4,000 to complete. Yet, some more extensive systems  have been reported as high as $20,000.  You must take into consideration the price of tanks, tubing, valves and pipes. Along with installation and permit and maintenance fees, these costs can increase greatly.

Are Permits Required for Simple Greywater Systems?

Yes, in most cases, any system that collects greywater from bathroom showers, sinks or bathtubs is required by law to have a permit. This is also true of any greywater system that alters a home's existing plumbing or framework. Be aware, laws and specific requirements can vary from state to state. Always consult your local enforcing agency before beginning any greywater project.

Greywater System vs Greywater Recycling System 

greywater recycling components
    With a few notable exceptions, a greywater recycling system functions in much the same manner as a simple greywater system. Waste water from bathtubs, showers and non-kitchen water basins is reused for irrigating landscapes and flushing toilets. To be clear, neither is safe to drink but there are some discernible differences. What differentiates a greywater purification system is that all water is treated and disinfected before being reused. This reduces contamination risks and increases usage capabilities. When water from a greywater system is dispersed for irrigation, it still contains low levels of bacteria and viruses. For this reason, precautions must be taken when using water for irrigation. A normal greywater system must disperse water at the drip line and never be used in a standard sprinkler system. Doing so could pose a danger by releasing contaminants into the air. Because greywater recycling systems filter and sanitize greywater, sprinkler systems are safe to use. Standard greywater usage must not be used to irrigate vegetables or fruits that may come in contact with or the soil. This includes all produce that grows near or under the ground level. Conversely, water recycled in a greywater treatment system can safely be used to irrigate all vegetables, fruits, lawns and flower gardens.

Greywater System Benefits

Greywater systems can contribute to a more sustainable environment and household  
  • Reduce freshwater consumption - Household greywater systems can lower fresh water usage by 15 - 45%. Preserving this valuable natural resource is essential to maintaining a healthy environment.
  • Lower demands on local water treatment plants - Greywater systems divert waste water away from sewage systems and septic tanks.
  • Beneficial during times of drought - Greywater systems keep grounds irrigated during periods when fresh water is scarce.  They do so without depleting potable, fresh water supplies. As temperatures continue to rise across our country, safe, sustainable practices are in everyone's best interest.
  • Lower water bills - Reduced  fresh water consumption  can save home owners money. Of course this savings  accrues over time once the initial cost of the greywater system is recouped.

Greywater System Challenges 

Responsible system management of a residential greywater requires adherence to strict safety guidelines. 
  • Greywater storage -  Untreated greywater has a very short shelf life.  It should not be stored for longer than 24 hours before being reused. Longer periods of storage allows bacteria to build, causing greywater to take on a foul odor. If longer storage time is unavoidable, adding two tablespoons of chlorine bleach per gallon of water will stave off contamination for a brief time. That said, for safety sake, it is imperative to disperse gray water as soon as possible.
  • Avoid  over saturating lawns and gardens with greywater - Excess greywater allowed to pool  or run off from lawns or gardens pose a danger to people or wildlife.  
  • Long term irrigation with greywater may have negative impacts on the environment.. Accumulation of salts, surfactants and boron can deplete safety of soil deposits. Prior treatment of greywater before irrigation is always the most prudent tactic. For those truly interested in preserving our environment, a full greywater recycling system may be worth considering.
  • Never use a sprinkler system for untreated greywater - Sprinkler systems can potentially put dangerous greywater bacteria and viruses into the air. Unless greywater has been previously filtered through a recycling system, Greywater irrigation systems must distribute water below the ground surface by way of a suitable drip irrigation system or drainfield.  A drainfield, sometimes referred to as a greywater leach field, is a rock filled trench built for safe greywater disposal. 

Conclusion:

Household greywater systems can contribute to a more sustainable earth by reducing the amount of fresh water we consume. Conserving one of our most valuable resources is vital to the environment and the communities we live in. Yet, reuse of greywater does not come without its share of concerns and issues. Long term questions linger regarding possible negative impact of dispersing greywater into the soil. Still, advancements in greywater recycling systems show great promise and the benefits seem to out way the potential risks. As technology develops, look for greywater systems to become more commonplace in the future.
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