Waste Not, Want Not: Mastering Residential Greywater Systems

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Greywater systems help you to conserve water, reduce your water bill, and reduce the environmental impact of your water usage.

Here, we’ve shared everything you need to know about residential greywater systems, including what they are, how they work, their benefits, and more.

πŸ“Œ Key Takeaways:

  • Greywater is wastewater that comes from your bathroom and kitchen sinks, showers, bathtubs, dishwashers, washing machines, and other water-using appliances and fixtures (excluding toilets).
  • Residential greywater systems store greywater and treat it for non-potable reuse, from laundry to landscape irrigation.
  • When choosing between greywater recycling systems, consider your budget, your current use of cleaners/detergents, your intended greywater reuse, the system capacity, and more.

πŸ”Ž What Is Greywater?

Greywater is the wastewater generated from most water-using fixtures and appliances in your home, including your bath water, shower water, handwashing sink water, laundry water, and dishwashing water.

The only wastewater in your home that isn’t greywater is water from your toilet (see “Greywater Vs Blackwater” below).

Greywater isn’t the same as potable water because it isn’t safe for drinking. It often contains small amounts of detergents, soaps, shampoos, shower products, and household cleaners. It may also contain traces of dirt, food particles, microorganisms, hair, and skin cells.

The exact composition of greywater depends on the source of the water. For example, your shower water will contain different impurities than your dishwashing water.

Because greywater is relatively low in contaminants, you can reuse it for certain purposes – as long as it has been properly treated and filtered. And that’s where residential greywater systems come in.

By reusing your greywater rather than sending it into a sewage system or septic tank, you can conserve water and reduce your water bill.

Residential greywater system

Greywater Vs Blackwater

Greywater is different from blackwater – the water that comes from your toilet.

Blackwater can’t be reused, and it shouldn’t be treated in a greywater system. Blackwater is sewage and likely contains dangerous microorganisms and other nasties that you don’t want to introduce to your greywater treatment system or use for any purpose on your property.

It’s essential to distinguish greywater from blackwater and divert blackwater to your sewage or septic system to prevent cross-contamination of these water types.

πŸ“₯ What Is A Residential Greywater System?

Greywater isn’t suitable for non-potable use until it has been correctly treated to remove sediments, detergents, and other likely contaminants. The easiest method to remove these impurities is to install a residential greywater system.

A greywater system, otherwise called a greywater recycling system or a greywater irrigation system, is a plumbing system that’s designed to collect, filter, and reuse wastewater generated from various household activities.

Instead of sending this relatively clean water into your sewage or septic system, a greywater treatment system diverts it for reuse.

Illustration of a residential greywater system

Components Of Greywater Recycling Systems

Some of the common components of a greywater system are:

  • Pipes & Plumbing For Greywater Collection. The system collects greywater from specific sources in your home, such as showers, bathtubs, bathroom sinks, dishwashers, and washing machines. You’ll probably need to install some new pipes and plumbing to divert the greywater from your existing plumbing to a separate collection point. You might also need to install a pump if gravity alone won’t send the greywater all the way to the collection tank.
  • Storage Tanks/Containers. This collected greywater is stored in tanks or containers before it undergoes treatment. Different greywater systems have different storage capacities. The bigger the capacity, the larger the storage tanks, and the more water that can be stored at any time for various reuse applications.
  • Treatment and Filtration. Before it can be safely reused, greywater needs to be treated to remove various contaminants and impurities that could affect water quality. There are various treatment methods that you might find in greywater systems, including physical filtration, settlement of sediments, aerobic or anaerobic digestion, separation of lighter solids, chemical or UV disinfection, or a combination of these techniques.
  • Distribution Pump & Pipes. The treated greywater is then distributed to its intended reuse point (such as an irrigation system or a toilet for flushing). Again, you may need separate plumbing lines or pumps to transport the greywater to different parts of your home or property. If you use a pump system, this will automatically pump the water to the point of use.
  • Safety Features. A good greywater system should also incorporate a number of safety features to prevent cross-contamination with black water or potable water. The manufacturer may instruct you to install a backflow prevention device or appropriate plumbing connections to prevent the greywater from mixing with other water types.

The design of a residential greywater system varies depending on a few factors, including your household water usage, your available space, what you want to use the greywater for, and any local regulations that might affect the system you buy.

Simple greywater systems have a more basic design that may include gravity transportation of water to the surge tank, and a pump for hand-pumping the recycled greywater to the suitable end location.

Other greywater systems are more complex and use more advanced treatment technologies and built-in pumps to automate the process and provide fresh water for a variety of uses.

Regardless of the greywater system that you choose, it’s important to make sure that the system is designed and installed in accordance with your local regulations. You’ll also need to properly maintain and monitor the system to maintain optimal performance and minimize environmental and health risks.

πŸ€” Why Use A Residential Greywater System?

With landscape irrigation accounting for nearly one-third of all residential water use, it’s no surprise if you want to cut back on how much clean, fresh water you’re using for outdoor purposes.

You may as well recycle your home’s greywater for reuse outdoors, and this has a few obvious benefits:

  • Your water bill will be less because you’ll be using the same water supply twice for different purposes.
  • You’ll be able to save money and help with conservation, either supporting your local water utility (if you’re on a city water supply) or conserving your own private well or rainwater resource.
  • Diverting greywater away from sewage systems and treating it appropriately before using on your property helps reduce surface water pollution.
  • You’ll have better drought resilience because you won’t have to cut out your irrigation and other outdoor watering tasks as these don’t require any extra water on top of your household uses.

There are various sizes and designs of residential greywater systems, so you can choose a system that best suits your requirements and preferences.

Reusing greywater for lawn watering

🚰 What To Do With Your Treated Greywater

Some of the different ways to reuse greywater include:

  • Landscape irrigation
  • Toilet flushing
  • Pressure washing a driveway
  • Cleaning and other household tasks
  • Washing your car

… and other non-potable water needs.

Essentially, reusing greywater for any purpose is fine, as long as the greywater isn’t used for drinking, cooking, or any other potable use.

πŸ“ What To Consider Before Installing A Greywater System

Before you install a greywater system in your home, consider the following things:

Your Budget

First, make sure you can comfortably afford the upfront cost and maintenance costs of owning a residential greywater system.

Greywater systems cost $1,000-$5,000 on average, depending on the system size, complexity, and capabilities. However, some basic systems for a single appliance or fixture cost as little as $100-$300 – so price depends on the unit size and intended purpose.

There’s also the cost of a professional installation, which is around $250-$1,000, depending on the scope of the installation required. If you’re considering installing the system yourself, you can do this for as little as $100.

Ongoing maintenance costs may add up to several hundred dollars per year, again depending on the type of system you buy and the upkeep it requires.

Your Intended Greywater Reuse

What do you plan to reuse your greywater for? This will determine the type of system you buy and any precautions you should take with the use of cleaners and chemicals in your home (see below).

For instance, if you just plan to use your greywater for non-irrigation purposes, such as pressure washing your drive, washing your car, or flushing your toilets, you don’t need to worry about keeping your greywater free from the likes of chlorine bleach and certain soaps. You’ll still need to filter it to remove debris.

But if you plan on establishing a greywater irrigation system, especially if you’re growing fruits and veggies that you will eventually eat, your greywater needs to be adequately treated for outdoor irrigation use – and you’ll need to be careful with what you add to your water before it enters the greywater system.

Greywater irrigation system

Your Current Use Of Cleaners & Chemicals

To ensure your greywater is safe for reuse after treatment and to prevent damage to your greywater system, you may need to switch up the cleaners and chemicals you use in your home.

Any detergents, soaps, and cleaners you use should be non-toxic and biodegradable. They should also be free from boron (borax) and sodium, since these ingredients are often harmful to plants and soils.

Additionally, don’t use cleaning products that contain chlorine bleach in your sinks and other water-using fixtures and appliances if the bleach water will end up being treated in your greywater system. Bleach is a cleaning chemical that’s harmful to plants, so it shouldn’t be present in greywater used for irrigation purposes.

You also need to consider how soaps might affect the pH of your greywater. Some bar soaps increase water’s pH, which could be harmful to plants that prefer an acidic environment, like blueberries, rhododendrons, and ferns.

If in doubt, when cleaning or using certain soaps, divert the greywater to your sewage or septic system to prevent contamination of your existing greywater supply.

DIY vs Professional Install

Are you planning on installing your own system for treating greywater, or would you prefer to hire a professional?

Installing your own system will take more work, and we only recommend this option to people looking to install simple systems that don’t require a complex install.

Hiring a professional to install the system is more expensive, but it’s the hands-off solution that gives you the guarantee of a proper install job, and you might be able to use the same professional for maintenance and servicing. Plus, a professional installer can advise you on the best system for your situation.

If you’re not sure whether you’ll be capable of installing a greywater reuse system yourself, check the user manual for the installation steps. If there are a lot of complex processes involved, it’s best to hire an expert.

System Capacity & Your Available Space

Different greywater systems have different capacities, and the right-sized system for you depends on two things:

  1. How many sources you plan to get your water from (i.e. are you hooking the system up to just one fixture or appliance, or do you want to take greywater from all your fixtures and appliances?)
  2. How you plan to reuse the greywater (i.e. do you just want to use it for a single purpose, such as reusing laundry water in your washing machine, or do you plan to use it for multiple purposes, like irrigation, cleaning, and other outdoor uses?)

While you’re thinking about your requires system capacity, also make sure you have enough available space in your home for installing the system and all its components.

The unit itself isn’t the only thing to make room for. Depending on the system design, you may also need space for distribution pipes, pumps, and any other important equipment.

Check your available space and take measurements, then compare these to the system’s dimensions to make sure you have enough room to house the unit. Remember, you’ll need some extra room around the system to give you enough space for installation, maintenance, and possible modifications in the future.

Greywater system construction

πŸ‘Ž Setbacks Of Greywater Systems

You’ve heard a lot of good stuff about residential greywater systems so far, but in order to get a balanced overview of these systems, we also need to discuss their possible setbacks.

Here are some of the setbacks of a greywater system:

Can Be Expensive

If you want a greywater recycling system that will significantly reduce outdoor and indoor water consumption, you’ll likely spend upwards of $1,000 upfront – and that’s not including the cost of a professional installation and any amendments to your household plumbing that are needed.

Require Routine Maintenance

You can’t install your greywater system and promptly forget that it exists. Most greywater systems require regular maintenance, including inspecting and cleaning the filters, distribution lines, and pumps, and fixing issues (such as clogged components) when they arise.

Regulatory Compliances

Depending on where you live, your state or local authority might have regulations on greywater reuse that you need to comply with. Make sure to thoroughly research any local regulations before you spend your money on a greywater recycling system.

Long-Term Value Varies

The upfront cost of a residential greywater system might not be worth the long-term value, depending on your situation. For instance, if you live in a region that gets plenty of rain, it probably makes more sense to install a cheaper rainwater collection system to capture water for irrigation purposes, rather than spending thousands on a greywater system that requires ongoing maintenance.

πŸ– Our Top 5 Tips For Reusing Greywater

Greywater is unique from any other water type, and there are specific recommendations for its reuse.

Here are our top tips for reusing greywater:

  1. Don’t store unused greywater for any longer than 24 hours. When left too long, the impurities in the water will start to release odors.
  2. Avoid drinking the water. There’s a possibility that greywater could contain pathogens, which is why greywater systems typically deliver water straight to an irrigation system, where the water soaks into the ground and isn’t used for drinking purposes.
  3. Don’t allow the greywater to pool on the ground or run off. You’ll provide mosquito breeding grounds if your greywater doesn’t soak properly into the ground.
  4. The simpler, the better. If possible, choose a simple gravity-based system that don’t use pumps. These systems will require less maintenance and will typically last longer and use less energy to run.
  5. Install a 3-way valve to switch between sewers/septic systems and the greywater system. This is the easiest way to divert water to your greywater treatment unit.
Waste water system quality

πŸ“‘ Final Word

So, now you know the ins and outs of residential greywater systems – are they worth the money?

We think greywater systems are ideal for people who use hundreds of gallons of water for irrigation and other non-potable purposes every year. In this case, it just makes sense to use recycled greywater from your home rather than using potable drinking water, which unnecessarily increases your water bill.

Of course, make sure that a greywater system is within your budget, you have plenty of room to install the system, and you’re prepared for the ongoing maintenance, before you spend your money.

❔ Residential Greywater Systems FAQ

Is greywater safe for plants?

Yes, greywater is typically safe for plants, as long as you use non-toxic cleaners and soaps, and avoid any products containing chlorine, sodium, and boron. In fact, the traces of dirt, food particles, and skin cells in greywater can actually be beneficial to plants, acting as nutrients and helping to encourage healthy plant growth. You can even safely use greywater in vegetable gardens – just make sure that the water doesn’t come in contact with anything edible on the plant.

Do I have to treat all my greywater in a greywater system?

No. If your greywater contains dangerous chemicals or you just don’t want to treat it in your greywater system for whatever reason, you can divert it to your septic or sewage system. Most greywater systems have a valve that lets you send water to the sewer if, for whatever reason, you don’t want to use it.

What do you do with unused greywater from a greywater system?

It’s unlikely that you’ll use so much greywater that you have unused water in your system that you need to get rid of. If you do have an abundance of water, just use it in your irrigation system – soil can soak up more water than you might imagine! If you don’t plan to use all your greywater, look at buying a branched drain system that you can turn on and off depending on your greywater needs.

Can you use recycled greywater for drinking water?

No, you shouldn’t recycle greywater for drinking purposes. Greywater can be reused for any non-potable purpose, from laundry to landscape and irrigation systems. However, even filtered greywater may contain impurities that make it unsuitable for drinking. Most people use greywater for sustainable backyard ecosystems 0 not for drinking.

  • Brian Campbell
    President & CEO, CWS, CWR

    Brian Campbell, a WQA Certified Water Specialist (CWS) and Certified Water Treatment Representative (CWR) with 5+ years of experience, helps homeowners navigate the world of water treatment. After honing his skills at Hach Company, he founded his business to empower homeowners with the knowledge and tools to achieve safe, healthy water. Brian's tested countless devices, from simple pitchers to complex systems, helping his readers find the perfect fit for their unique needs.

  • Jennifer Byrd
    Water Treatment Specialist

    For 20+ years, Jennifer has championed clean water. From navigating operations to leading sales, she's tackled diverse industry challenges. Now, at Redbird Water, she crafts personalized solutions for homes, businesses, and factories. A past Chamber President and industry advocate, Jennifer leverages her expertise in cutting-edge filtration and custom design to transform water concerns into crystal-clear solutions.

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