“We never know the worth of water till the well is dry.”
~ Thomas Fuller

This a Pretty Big Post so I Broke it Down into six sections with a navigational  Table of Contents so that you can easily jump to what you are looking for.

Before We Get Started...

My goal is to give you simple clear instructions to implementing a working greywater system for your home as quickly as possible. 

However, no matter how hard a writer of a 'How To' article tries to cover every detail of a DYI project sometimes end users will have circumstances that don't match the instructions being given.  In these cases acceptations to their circumstances need to be made as it is of course impossible for the author to know every acceptation out there.

Whenever you are unsure about any step provided and before you take any action  please contact a local professional to assist you in installing a safe and reliable system.

On Average 2/3 of the water used in Every Household Results in Greywater


What Exactly Are Greywater Systems?

In a nutshell, a typical residential greywater system collects greywater from one or several sources in your home (i.e. washing machine, utility sink, bathroom sink/shower) and delivers via distribution/irrigation piping to your landscaping.

Benefits of Greywater

  • Re-use for Irrigation and Gardening
  • Toilet Flushing
  • Washing Laundry  
  • Swimming Pool Supplementation
  • Emergency Back-Up
  • Reduces Freshwater Consumption
  • Lowers Your Water Bill and Saves You Money
  • Treated Greywater Provides Beneficial Nutrients for Growth of Plants
  • Reduces the Load on Septic Systems Extending Their Life Cycle
  • Reduces the Load on the Municipal Sewer System Mitigating the Need for Expansion
  • Saves Energy at the Municipal Treatment Level Because Less Greywater Needs to be Treated

Why Do We Need Greywater Systems?

Sooner or later we will run out of available drinking water if the non-stop overuse of fresh water for non-essential tasks is continued.

Our planet’s water needs are rising rapidly causing shortages of potable (drinkable) water and  increasing the pressure to find alternative water supplies.

The problem is found in almost every country today and more than 1.2 billion people do not have the access to clean and fresh drinking water and this number is growing year after year.


Australia has implemented a four-stage water restriction program that include restrictions on watering lawns, using sprinkler systems, washing vehicles, hosing pavement, refilling swimming pools. 

South Africa

Cape Town, South Africa running out of water effecting over 4 million resident with no access to water like in the Meatu district of the Shinyanga region of Tanzania, forcing people to dig holes in the sand of dry riverbeds to obtain drinking water. The water they are obtaining is not safe to drink but it is the only access to water they have.

The Greywater Solution

By practicing proper greywater management techniques, we can re-use greywater for non-essential tasks which in turn allows fresh water to be available for human consumption.

Greywater can replace fresh water that is used for non-essential tasks like washing autos, spraying off driveways and irrigating status lawns.

Unlike a rainwater harvesting, which obviously requires rainfall, a greywater system never runs short of water and is a predictable safe water source. Reuse of it will helps preserve fresh water sources of water for present and future use.

The more of fresh water you use, the more greywater you generate.

The Average Amount of Fresh Water Used by a Westerner is between 2,400-3,000 Gallons a Month

What's Legal in Your State?

There are risks involved in the use of greywater, so a system needs to be installed and managed per code.

There are some municipalities that do not like greywater reuse because it reduces the amount of water that is returned to them for treatment and re-use.  If you install your system incorrectly it could be in violation of your local codes and an inspector could make you tear  your entire installation out.

Greywater codes vary depending on where you live. In some states the code is very progressive and unfortunately in other states there still is a lot of work to be done.  If you live in a state that has not sufficiently addressed greywater codes, please contact your legislators with your concerns.

To help you quickly access your states information on codes please use the interactive map I have provided below.

Simply click on your region and then click on your states name which will take you to the most current code information I could find for your state.  

The states are divided into two groups; States without formal greywater regulations and States allowing greywater reuse.  I have indicated after each states name which group your state falls into.

Types of Codes

As you research your states greywater codes use the two following definitions to help guide your understanding of what kind of code structure your state has.

Performance-based codes: (also known as outcome-based) define the requirements for greywater systems.  Those systems which meet the requirements are legal and all others are illegal.  Performance-based codes are simple and typically do not require permits or inspections and their associated fees.  However, sufficient legal leverage is given for the city to enforce compliance.  

Prescriptive Codes: Specifies exactly a certain standard of how each component of a greywater system is to be constructed and operated.

If Every State in America Adopted Simple Greywater Codes it Would Result in a 600 Million per Day Reduction in U.S. water consumption of Fresh Water


Main Objectives

  1. 1
    To create water security by using greywater to reduce the demand on fresh and rainwater harvesting sources.
  2. 2
    To manage greywater to prevent groundwater contamination from surface pooling and seepage into sub-soils.

Rural Areas

It depends on the situation but most locations in a rural setting do not produce greywater in high concentrations. People living in the country have septic tanks or leach fields and use wells and/or have access to other natural sources of water. For most living rurally greywater management usually
holds little interest.

Urban Areas

Since populations are higher in urban centers, we can expect greywater to be produced at higher concentration as well as the accompanying pollutants.

With so many residences and buildings per square foot there is limited space for greywater systems to be installed.  Implementation of urban greywater systems requires innovative consideration as currently the demand for greywater within this environment is lower than its production.

Indoor Uses

In the built environment the two major consumers of water are toilets and washing machines.  Before using greywater as source water for these purposes proper filtration and disinfection is required.

Outdoor Uses

Industrial/Commercial: After greywater has been properly treated it has multiple uses at the Industrial/Commercial levels. Properly treated greywater has no foul odor, so it can be used at car washing centers, commercial pressure cleaners and high-pressure water cutters.

Landscape features, gardening, and irrigating fields: Greywater restores nutrients that are beneficial for plants. Avoid concentrating greywater in one area of the garden, this will result in increased salt content in the soil and can adversely affect the health of your plants.


Some plants do well with greywater, but you will need to research your own plants.  Here is a quick list of common plants that do well with greywater:

Currant, raspberry, blackberry, gooseberry, filberts, rhubarb, elderberry, passion fruit, kiwi, hops, and grapes. Blueberries, Yaupon, Smooth Sumac, Ceanothus herbaceous, Yucca glauca, Stretch berry, Redroot, Atlantic ninebark, Fragrant sumac, Scarlet globemallow, Dwarf palmetto, soapweed yucca

Do and Don’t

  • Do wash your hands properly after handling greywater.
  • Do system maintenance/repairs asap.
  • Do use the correct kind of soaps. 
  • Do not use greywater to water vegetables that are being eaten raw.
  • Do not let animals or humans drink untreated greywater.
  • Do not let greywater make direct contact with the plants.
  • Do not use hot greywater for irrigating purposes, it may kill the various
    organisms present in the soil that are beneficial to plants.
  • Do not use greywater for indoor purposes without treating it properly

Give Back

As more greywater is diverted for reuse municipal sewer systems will see an increase in blocked sewer lines.  Greywater plays a big part of turning solids into liquid so their easier to pump, therefore it is a good idea to occasionally divert some of your greywater back to the municipal system.

Mixed not Shaken

A question often asked is can rainwater be mixed with rainwater and the answer is yes and no.

Yes, if you have treated your greywater and you intend to irrigate with it. Collected rainwater should be treated like gold, to avoid cross contamination it should be mixed with greywater in a separate barrel/cistern from the rainwater harvesting system.

No, if you have untreated greywater. 

Mixing, treating and reuse of rainwater and greywater is best left for an pre-engineered skid.


To avoid odor emitting from your greywater system simply use the water within a 24-hour period. 

A greywater system should be set up so that it is delivered from its source to its destination immediately

IMPORTANT: Flush a system at least one per day to mitigate odor and pathogen/bacteria growth.

The Environment and Greywater

This is extremely important topic.  If precautions are not taken you could be putting greywater on your plants that has a high level of sulphates derived from using the wrong kind of soaps.

Extended sulphate build-up will deteriorate the quality of your soil. 


Only use low sodium soaps.

No bleach.

pH neutral soaps


What's in Greywater?

In the built environment, occupant water use behaviors are the key contributors in greywater composition. The various components found in grey water are:

• Pathogens
• Various metals and pollutants
• Various Nutrients

Let’s give each of these a closer look:


The World Health Organization (WHO) and the United States Environmental Protection Agency (USEPA), the US Agency for International Development (USAID), Mexico and Germany all have set standard guidelines for grey water quality and handling.

However, the International Development (USAID) USEPA and USAID have set extremely strict guidelines for treated greywater reuse. Unrestricted irrigation of crops meant for human consumption is to have no detectable fecal coliform bacteria present for every 100 mL of water. For commercial irrigation and use on fodder crops the allowable limit is < 200 cfu/100 mL.

Metals & Pollutants

Various metals found in grey water are, but not limited to:

• Mercury
• Lead
• Nickel
• Cadmium

Though the amount of these metals and toxic pollutants found in grey water is generally low, they may be found in higher concentrations dependent upon location and use.

Human behavior is the main catalyst in the contribution of pollutants into grey water so good choices need to be made like using environmentally friendly materials or looking for ways to eliminate harmful constituents. Simple behavior changes can have dramatic effects on lowering or eliminating metals and pollutants making it easier to treat and re-use grey water.


The use of grey water nutrients depends on which nutrients and in what quantity they are present, i.e. nutrients like phosphorous can affect the water quality.

It may seem like a promising idea to have nutrients in grey water, but it depends on which nutrients and in what quantity they are present i.e. nutrients like phosphorous can affect the quality of the water.

The main source of phosphorous in grey water is washing detergent, therefore detergent use within households can contribute a considerable amount of phosphorous into the water.

As a result, many countries have banned the use of detergents containing phosphorous because elevated levels of phosphorus will cause algae to grow faster and interfere with the balance of the ecosystem resulting in a decrease in water quality, habitat and food resources. 


Design considerations

Greywater is predictable and easy to calculate the amount of available water for re-use. This is an important first step in understanding how much potential water is available for re-use.

So first you'll need to calculate  annually your potential greywater capture is...

How Much Grey Water Do You Produce?

The important question is, how much grey water does your house produce?

It varies greatly within households, depending on lifestyle and routine. However, for a quick estimation, a safe rule of thumb is to use sixty percent as an average to calculate the amount of grey water produced in the average western household.


As an example, let's take a family of three that use 100 gallons/day 365 days a year.

To get your daily consumption number:

Multiply 3 (People) x 100 (Gallons) which equals 300 Gallons/Day

To get your annual consumption number:

Multiply 300 (Gallons) x 365 (Days) which equals = 109,500 gallons a year

To get your annually potential greywater re-use number:

Multiply 109,500 (Gallons) x .60 (Average greywater production) equals 65,700 gallons of grey water annually available for potential capture and re-use.

Now that you have determined the amount of greywater your site produces in a day you next need to calculate your soils percolation rate.

Percolation Test

A Percolation Test is used to determine how quickly your soil absorbs water so you don’t flood your plants. The rate is the average time in minutes that it takes for water to drop by 1 inch.

Basically, it consists of digging a hole(s) in the soil where the greywater will be used. Then thoroughly soaking and filling the hole with water to timing how long it takes for the water to percolate into the soil.

Once you determine your percolation rate then you can calculate the number of gallons a distribution point can handle. 

It is a good rule of thumb to design your distribution points to be able to handle approximately 20% over your daily greywater output.

EXAMPLE:  If the water in a hole takes 30 minutes to drop 2 inches then you simply divide 30 (minutes) by 2 (inches) for a percolation rate of 15 minutes per inch (mpi).

Gravity is Your Friend

I know it seems obvious, but the goal is to get your system to drain as easily, completely, and quickly.

Always layout your pipe runs so that the drain away and not towards your home. 

Use gravity to your advantage every place you can in your design.  Take advantage of downhill runs where momentum will do the work for you.

Dig your trenches deeper the further away you get from your point of origination to ensure proper drainage.

Feeling a little Drippy?

You can use drip irrigation with greywater, but it needs to be treated and filtered first.

To Filter or Not to Filter?

I have seen installations with and without filtrations, guess which ones had more problems?

I recommend filtering your greywater before reusing it.  Filtration will remove two of the biggest culprits of a greywater system, lint, and hair.

Filtration protects the system components, prevents blockages, and provides cleaner water to your yard.

Types of Filters

Woodchip Bio-Filter

Traps grease and food particles from a kitchen sink. The top half of the inlet pipes has been cut off to allow the greywater to flow over the edges and distribute into the wood chips.

Mesh Bag Filter

Greywater is first passed through a coarse mesh filter bag. This removes any large particles such as lint and hair immediately. The greywater is then passed through a much finer filter to remove the small particles.

Slow Sand Filter

A slow sand filter removes the smallest particles. A slow and constant flow of water through the filter described above leads to biological activity as the top layer of sand traps micro-organisms (e.g. bacteria). “bio-film builds up on top of the sand.”

Inline Filter

There are a plethora of commercial inline filters available on the market.  Inline filters are typically installed in more sophisticated systems but be can used in the typical residential system.  If you are unsure about what inline filter is right for your system I highly recommend that you discuss your options with a local professional before purchasing.


How long can you expect a greywater installation to take?

This will, of course, depend on how complex of a system you are going to install.

If you have all your parts and pieces assembled, it could take as little as one day or as long as a week for more complex systems.  On average though a simple system can be installed in a weekend.

There are preassembled greywater skids that you can order and have delivered to your site.  The skids come pre-engineered and ready to be connected to power and piping. This option is usually used in large residential, commercial, or industrial applications.  

Do You Need to Call a Professional?

This is contingent upon a couple of things:

Your competence level with DIY plumbing projects.

How accessible and the location of the connection points.

The type of system you install.  The shower bucket to landscape technique only requires your willing to shower with a bucket and the brute strength to carry it out to your yard.  Even the simple laundry to landscape system requires you to assemble pipe and fitting.  And of course, more complex systems should involve a plumber and even possibly an engineer.

Bottom line:  If you have any reservations about installing a system get a professional involved.  The cost of hiring a plumber will pay back ten-fold in peace of mind, reliability, and legality.


The cost of a greywater system varies from depending on your location and type of system you want to install and the volume of greywater to be processed.

There are preassembled greywater skids that you can order and delivered to your site.  The skids come pre-engineered and ready to be connected to power and piping. This option is usually used in large residential, commercial, or industrial applications and can be quite expensive.

I highly recommend you start small and design for expansion.  Smaller systems will cost less and require less maintenance.  If you need more capacity you can add it when necessary.

I don't like to give out vague cost estimates because some people will spend money to have only the newest and the best while others are content to hobble together the parts and pieces needed for almost nothing.  

None-the-less I'll give you a range:

Inexpensive/Small:  $75-100

Intermediate/Large: $100-$1,500

Complex: $1,500-10,000+

10 Basic Steps to Laying Out a Greywater System

  1. 1
    Calculate your potential greywater capture re-use and what your soils percolation rate is. 
  2. 2
    Obtain pertinent dimensions for you layout.  You need to know the distance from the source point to the furthest distribution point.
  3. 3
    Note any increase in elevation you'll encounter and determine what kind of system you'll need to install to get water up a slope
  4. 4
    Take the time to top sketch out your system and create a complete parts list and budget.
  5. 5
    Mark with stakes and twine  were trenches will be dug and where valve boxes are to be buried.
  6. 6
    Install all piping and fittings within the home first working outward to the distribution points
  7. 7
    Dig all of your trenches below your frost line and fill the bottom with 3" inches of loose gravel.
  8. 8
    Install your piping and check all connections.  Before covering the pipe test system with water to in sure there are no leaks. 
  9. 9
    Cover pipes with another 3" of loose gravel
  10. 10
    Cover the gravel with soil  until the trench is flush with the rest of the yard.


Let's Be Honest

If you don't have a lot of experience with grey water and/or plumbing the less complicated and more affordable I can make the steps the more likely you are to take action.

Since my goal is to get you installing a grey water system as quickly and easily as possible, I am going to focus on the basics of each kind of system.  You can always expand or add to your system once you have a working system in place.  It’s harder to tweak a complicated system than it is to amend a simple one.  So, when selecting the type of system, you want to install, keep It simple.

If you have previously researched greywater systems, you most likely have discovered there are several different types of systems with differing options and details.

For the uninitiated it can be a little confusing as to what kind of system is right for them and what options are necessary or can be omitted.

I struggled with how to tackle this problem so that you can as quickly as possible get your greywater system up and working. 

What I landed was simplicity.  

Following are six of the most common  types of greywater systems:

The Simplest of Systems

The simplest type of greywater system is a bucket or dish basin, I know that it’s not very exciting, but it gets the job done. 

All you need to do is simply collect the water from your sink/shower and carry it out to your plants and trees.  As with all systems make sure to use environmentally friendly soaps (See section on soaps) and don’t overwater one particular spot in your yard.

A Surge Tank System

The next simplest system is using a surge tank.  Surge tanks can be added to other types of systems as well but can also be used as a stand alone system.

It’s pretty simple to build but may need a little tinkering to get working properly.  As you can see from the image below/above it works based on utilizing gravity to push the greywater out to your landscaping.  On the outlet side you can either run hard piping or a garden hose to dispute the water to your yard.

Some systems have a surge tank placed between the washing machine and the distribution piping, but it is not necessary for the system to work. In the Laundry-to-landscape diagram below you can see I did not add a surge tank to my system but instead designed it so the catchment area at the top of my sand filter has sufficient room to hold water from a full load of laundry. 

An example of a surge tank can bee seen in the diagram located below under System Type #5, Branched Gravity System.

A Simple Laundry-to-Landscape System

A really popular greywater systems, the one I personally installed, is the laundry-to-landscape system originally popularized by Art Ludwig in his book Create an Oasis With Greywater.

One of the benefits to installing this kind of system is that there is no need to alter your existing plumbing.  The system uses the power of your washing machines built in pump to distribute the greywater to your landscaping.

A typical washing machine pump can pump water up to a height of 3’ and horizontally up to 100’ via 1” tubing. You should not use tubing or piping less than 1” in diameter because larger tubing/pipe provides lower resistance to flow.  When selecting your tubing remember polyethylene tubing is the most environmentally friendly tubing readily available for use in greywater systems

NOTE: An average residential washing machine produces between 10 and 25 gallons of water per load.  I personally have a high efficiency machine that produces 12 gallons of water from a large load.  The maximum number of gallons your machine is capable of discharging is important to know for calculating the size of a surge tank, sand filter and distribution. (see section on percolation testing)

It is also important to understand that a washing machines pump is only capable of pumping water a certain distance and/or height.  If you need to pump it further than this distance then you need to add an additional pump or utilize gravity, possibly both.

As shown in the diagram the greywater is pumped via pipe and tubing to mulch filled valve boxes at the point of delivery. The mulch filled valve boxes prevent the water from pooling or run off into undesired locations

Click on the image Above or on any system component Below to learn more.

A:   Washing Machine

You'll definetly need one of these.

B:   3-Way Diverter Valve

Click on Image for Additional Information

  • Quantity: 1
  • Size: 1"
  • Type: Valve
  • Style: 3-Way
  • Material: Brass
  • Inlet Diameter: 1"
  • Outlet Diameter: 1"
  • A diverter valve allows you to divert the greywater from being discharged from your laundry’s sewer standpipe connection to your landscaping. The diverter valve is one of the crucial parts of the system because with a turn of a handle you can divert the water back to the sewer if you need to take your system offline for maintenance or any other any reason.  The valve should be securely mounted to a wall where it can be easily accessed.

C:   Male Adapter

Click on Image for Additional Information

  • Quanity: 2
  • Size: 1"
  • Type: Schedule 40 fitting
  • Style: Male Adaptor
  • Material: PVC
  • Fitting: MPT x S (Threaded x Socket)

D:   Barbed Male Adapter

Click on Image for Additional Information

  • Quanity: 1
  • Size: 1”
  • Type: Schedule 40 fitting
  • Style: Barbed Male Adapter
  • Material: PVC
  • Fitting: MPT (Threaded) x Insert

E:   90 Elbow

Click on Image for Additional Information

  • Quanity: 5
  • Size: 1"
  • Type: Schedule 40 fitting
  • Style: 90 Elbow
  • Material: PVC
  • Fitting: Slip

F:   Tee

Click on Image for Additional Information

  • Quanity: 1
  • Size: 1"
  • Type: Schedule 40 fitting
  • Style: 90 Elbow
  • Material: PVC
  • Fitting: Slip

G:   Reducing Bushing

Click on Image for Additional Information

  • Quantity: 1
  • Size:  1 ½” x 1” PVC Reducing Bushing (SxS)
  • Type: Schedule 40 fitting
  • Style: Reducing Bushing
  • Material: PVC
  • Fitting: Slip

H:   Female Adapter

Click on Image for Additional Information

  • Quantity: 1
  • Size:  1 ½” 
  • Type: Schedule 40 fitting
  • Style: Female Adapter
  • Material: PVC
  • Fitting: FTP x S

I:   Auto-Vent

Click on Image for Additional Information

  • Quantity: 1
  • Size:  1 ½” 
  • Style: Auto-Vent
  • Material: ABS
  • Fitting: MP
  • Designed to break the siphoning action caused by draining water
  • An Auto Vent is designed to break the siphoning action caused by draining water. To be effective an auto vent must be installed downstream of the diverting valve and the highest point possible.  It needs to be connected to the main and close to the washer but located outside of the house.
  • If your distribution piping needs to be routed down before leaving the laundry room the system might still siphon even with an auto vent installed. To remedy this, you can mount the auto vent inside the laundry room.  However, if overflow happens, which is rare you will have water released into your laundry room. To fix this problem route ½” tubing the auto-vent outlet to your sewers standpipe.

J:   Barbed Adapter

Click on Image for Additional Information

  • Quantity: 1
  • Size: 1"
  • Type: Schedule 40 fitting
  • Style: Barbed Adapter
  • Material: PVC
  • Fitting: MPT x  Insert

K:   Barbed Tee

Click on Image for Additional Information

  • Quantity: 1
  • Size: 1"
  • Type: Schedule 40 fitting
  • Style: Barbed Adapter
  • Material: Acetal
  • Fitting: Insert

L:   Barbed Reducing Tee

Click on Image for Additional Information

  • Quantity: 6
  • Size: 1 ½” x 1”"
  • Type: Schedule 40 fitting
  • Style: Barbed Reducing Tee
  • Material: Plastic
  • Fitting: Insert

M:   Barbed Coupling

Click on Image for Additional Information

  • Quantity: 1
  • Size: 1 ½” x 1”"
  • Type: Schedule 40 fitting
  • Style: Barbed Coupling
  • Material: Plastic
  • Fitting: Insert

N:   Poly Tubing

Click on Image for Additional Information

  • Quantity: 10' Sections*
  • Size:  ½” 
  • Type: Schedule 40 fitting
  • Style: Poly Tubing
  • Material: Polyethylene

*Note: Tubing can come in pre-cut lengths or by the roll. Depending on how much you need and what your budget is you'll need decide which works best for you.

O:   Round Valve Box (Mulched)

Click on Image for Additional Information

  • Quantity: 6
  • Size: 8-3/8"
  • Type: Schedule 40 fitting
  • Style: Round Valve Box
  • Material: Plastic
  • All valve boxes need to be big enough to hold the amount water being distributed to its location.  See the section on percolation testing to determine the size you need but, in most cases, a 6” diameter box is sufficient.
  • The bottom of the valve box should be covered in mulch or woodchip 

P:   Barbed Green Back Valve

Click on Image for Additional Information

  • Quantity: 6
  • Size:  ½” 
  • Material: UV Stabilized Plastic
  • Secondary zone water diversion and flow control
  • Gravity irrigation flow valve
  • Up to 50 PSI

Q:   Existing Standpipe to Sewer

Stand pipe assemblies can differ depending on how a particular laundry room is plumbed.

In newer or remodeled homes you may see a washing machine outlet box embedded in the wall like this one:

Click on Image for Additional Information

You may have a utility sink like the one pictured below that your washing machine outlet hose releases into which is then sent to the sewer.

Click on Image for Additional Information

Still yet you may have a simple standpipe assembly like the one in the picture below.

In this set up the standpipe is connected to an old utility sinks sewer connection.

R:   Backflow Preventer

Click on Image for Additional Information

  • Quantity: 1
  • Size:  1"
  • Material: Clear PVC 
  • As the name suggests a backflow device prevents the backflow of grey water into your system.  Without a backflow preventer you run the risk of greywater flowing back into your washer creating odor and possibly ruining your laundry.

S:   Service Hose Connection Assembly

Click on Image for Additional Information

  • Quantity: 1
  • Size: 3/4"
  • Type: FHT
  • Style: Adapter
  • Connection: 3/4xS
  • Material: PVC

Click on Image for Additional Information

  • Quantity: 1
  • Size:  1"x1"x3/4"
  • Type: Schedule 40 fitting
  • Style: Tee
  • Connection: SxSxS
  • Material: PVC

This is a simple connection point where you can add a garden hose to blow out the line of debris to keep the pipes clear of obstructions.  

The connection should be installed downstream of the backflow preventer.

Once you have assembled the two fittings it should look like the image above.  The 3/4" adapter slip fits into the 3/4" leg of the Tee.  Be sure to secure the connection with plumbers glue.

To use you simply screw a garden hose into the treaded side of the adapter and you are ready to flush your system.

T:   Sand Filter (Optional)

This step is optional because the system will work without it.  However, if you are concerned about exposing humans or pets to unfiltered grey water than sand filtration is for you.

There are a lot of residential sand filters on the market for purchase but you can also  build one yourself  if you are a DIY type.

Buy or Build?

Buy: As stated above, there are a plethora of choices when it comes to purchasing a sand filter.  Below is an example of one that would work in this application:

Click on Image for Additional Information

  • Quantity: 1
  • Size:  40 & 50 GPM
  • Connection: 1  ½”   female pipe thread (FPT) inlet and outlet 
  • Up to 50 PSI

DIY: In-line Sand Filters are easy to build and operate.  The below image diagrams the simple components of a In-line Sand Filter.

Click on Image to Enlarge

Automatic Bypass (Freezing climate only) – Not Shown

For those of you living in climates that experience freezing you will want to install automatic bypass.

An automatic bypass is constructed of two wye type fittings that are joined at their horizontal connection points by a ball valve.  Two pipe runs of equal distance are installed at the wye fittings vertical connection points and run up to the maximum fill point of the tank. At the top of the vertical legs two 90-degree elbows are used to connect the two pipes.

This allows the water to rise up the 1st vertical pipe and overflow into the 2nd pipe if the line freezes with ice.  This prevents damaging the pump and flooding your laundry room.

Hose Service Connection (Not Shown)

This is a simple connection point where you can add a garden hose to blow out the line of debris to keep the pipes clear of obstructions.  The connection should be installed downstream of the backflow preventer.

Backflow Preventer (Not Shown)

As the name suggests a backflow device prevents the backflow of grey water into your system.  Without a backflow preventer you run the risk of greywater flowing back into your washer creating odor and possibly ruining your laundry.

Constructed Wetlands System:

I first learned the name of these systems as sludge monsters long before I knew they were called constructed wetlands.  I still often default to sludge monster.

The idea is simple, utilizing what mother nature gave us, hungry plants. The plants absorb nutrients and particles from greywater that they need.

The recommended constructed wetlands used in backyard systems is referred to as subsurface-flow or reedbed systems where the plants grow in gravel or soil.

The construction is typically a bathtub or galvanized stock tank with the bottom covered with gravel or soil for plants to grow in.  Next a layer of woodchips is placed over gravel/soil and then wetland plants are places into the substrate.

The key is to control the amount of greywater so that at peak it never rises above the surface of the woodchips.  This mitigates contact with the greywater and eliminates odor so you might need to add woodchips once the system is running.  If you estimate that your sites greywater output is going to overwhelm a 50-gallon tank system (ie. Two regularly used washing machines) you should conder adding additional tanks.

Examples of the kind of plants that do well are water hyacinth, cattails, bulrushes. To go deeper into what kind of plants that can be used and their functions I recommend speaking with your local nurseryperson.  It you really want to nerd out, here is a pretty cool source over at ResearchGate.

Gravity Branched System

A branched drain system is another type of simple system that uses gravity to distribute greywater to it desired endpoint.  It’s based on sloping the distribution piping downward ¼” inch drop for every foot it travels horizontally.

Although this is a simple system in concept it can be difficult to install because of the need to keep the source point above the delivery points.  It also requires you to alter or tie into your existing plumbing which can make it a financially unattractive option.

Pumped System

A pumped system sounds exactly like what you think it does, it uses a pump(s) to distribute grey water to your landscaping.  It’s used when gravity cannot be sufficiently leveraged to do the job.  Like if you need to move greywater up a slope and/or long distances to its distribution points.

A typical system is constructed of an effluent pump mounted on the bottom of a 50-gallon plastic barrel. The barrels inlet is located at the top of the barrel and once sufficient water has filled the barrel it is then pumped out to the distribution lines.

NOTE: Pumped systems require regular consistence maintenance and cost to operate.

FYI.  For large scale greywater pumped systems like ones used in hospitals, universities & apartment complexes you can order skid mounted multi-pump, barrel, and filtration systems. If you have a greywater system of this size it will need to be designed and installed by licensed professionals

Wrapping it Up

As you can see there are a lot of things to think about when selecting a greywater system for your home.  It's not rocket science but does require you to think through what you ant and how much you want to spend.

Check out my other post on How to Use a Washing Machine to Save Water & Money and What is a Greywater System? to learn about other ways to save water.

Please leave any comments below I'd love to hear your feedback.

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