What is Greywater?

Greywater action defines it as once used water generated from wash basins, showers and bathtubs. Shower water containing eco soaps, shampoos, conditioners, sodium and phosphates. Virtually  zero impact on plants and trees. The vast majority of plants thrive on nutrient rich greywater.

How can I use Greywater?

Greywater can be recycled/reused onsite for landscape irrigation.

Greywater differs from the discharge of toilets, which is designated Sewage or Blackwater containing human waste.

Is Greywater safe?

Recycled greywater is safe. Although never safe to drink, greywater contains dirt, a multitude of biological particulates and bacterias that our bodies and clothes shed. Containing nutrients, and pathogens, it is very important to discharge it below the surface in a layer of mulch for irrigation methods.

Are Greywater Systems legal?

Yes, and to ensure a complete safe application, we install greywater in two ways:

  • Directly from the sink through a branched drain system into the landscape received by natural filtration treatment of woodchip/mulch and soil.
  • Integrated filtration system, captures, filters and pumps greywater through a landscape drip irrigation system.

AP - Shower to flower


What soaps and other cleaning products can I use with a greywater system?

The PH of shower water is largely dependent on the type of shampoo used. While most shampoos are near neutral PH, some fruit based shampoos can be slightly acidic. Again the effect on PH overall is minimal due to dilution.Bio-degradable and non-toxic cleaning products should always be used. Avoid high salt (sodium) content and boron (borax). Non-toxic for humans but harmful to plants. Bar soaps tend to make greywater Alkaline, so use liquid soaps to maintain a neutral water pH. Anti-bacterial soaps should be avoided as they may kill beneficial bacteria living in the soil.

Isn’t the water Alkaline?

Greywater tends to have an approximate PH level of 10.5. alkaline greywater (approximately) when releasing the first wash water.  Repeated application of concentrated highly alkaline water to one or two areas of the garden will kill plants.

However, if greywater is irrigated evenly across the garden, the high PH water will not concentrate in one area, and is balanced by following rinse cycles. The overall PH level of washer machine water (including rinse cycles) is typically in the range of 8.0 – 9.0).

Water Softeners?

Water softening agents use large amounts of salt. Softened water should not be used in the garden.

Possible constructed wetlands can filter salts making water possible for irrigation purposes. This is a risk which may not work.

Fruit trees and vegetable plants grow exceptionally well with greywater. Greywater may contain bacteria, therefore its recommended to only eat fruit and vegetables grown above ground, not in direct contact with greywater.

Fruit and non bearing fruit trees have very little chance to come into contact with the greywater.

Greywater friendly plants:


Corymbia maculata – Spotted Gum

Pittosporum undulatum – Sweet Pittosporum

Assorted Fruit trees

Small trees

Acacia stenophylla – Shoe-string Acacia (inland Australia)

Casuarina glauca – Swamp she-oak

Melaleuca armillaris – Bracelet Honey Myrtle

Melaleuca huegelii – Chenille Honey Myrtle


Callistemon linearis – Narrow leaved Bottlebrush
Escallonia rubra – Escallonia

Westringia fruiticosa – Coast Rosemary


Cynodon dactylon – Couch grass (only average for waterlogging)

Stenotaphrum secundatum – Buffalo grass (based on experience with bath water)

Generally tough plants:
    • Atriplex cinerea – Coastal Saltbush (not tolerant of waterlogging)
    • Dianella caerula – Paroo Lilly (may be phosphorus sensitive)
    • Dietes grandiflora – Native iris
    • Gunnera manicata – Brazilian rhubarb (outrageous bog plant)
    • Juncus flavidus Rush – quietly charming Australian native, may be phosphorus sensitive
    • Limonium perezi – Sea lavender
    • Lomandra longifolia – Spiny headed mat-rush (may be phosphorus sensitive)
    • Goodenia ovata – Hop Goodenia (may be phosphorus sensitive)
    • Strelitzia nicolae – White Bird of Paradise



Greywater NON-friendly plants:
  • Grevillea
  • Bouganvillea
  • Camellias
  • Lavender
  • Herbs
  • Ferns
  • Azaleas
  • Vegetable seedlings
Will soap impact the fruits and vegetables?

Studies are yet to report on the measurements of soaps contained within fruits or vegetables grown with greywater.

Soap, shampoo and conditioner are diluted before the plants roots eventually absorb the water.

I personally irrigate, Tomatoes, Peppers, Berries and many fruit trees with greywater

Can I use Greywater on edible crops?

Where the edible part of the fruit or vegetable is above ground, and it is eaten raw, the greywater must NOT come into contact with the edible portions.

High flow rate drip lines apply the greywater direct and immediate to the soil zone. A 3-4 inch layer of mulch covers the dripperlines and soil, ensuring very minimal chance of the edible parts to be contacted by greywater.

Where the edible part of the vegetable is below ground (tuberous, potatoes, carrots, onions), filtered greywater will come into contact with the vegetable. If the vegetable is cooked before eating, the risk is removed by the cooking process.

What veggies should not use greywater?
  • Radish. Because the skin is rough, radish is difficult to clean. Commonly served unpeeled, there is a risk of bacteria remaining on the surface.
  • Salad onion (including scallions etc). Due to the onion’s layered structure, there is a chance (albeit small) of bacteria being caught within the onion, presenting a risk if eaten raw.
  • Potato carrot onion-  -All tuberous crops, with direct contact of greywater makes this vegetable highly susceptible to bacteria.
Key Points:
  • Do NOT store graywater for more than 24 hours; it can become septic within 24 hours
  • Only use laundry detergents that are Biodegradable and very low in sodium (salt).
  • Avoid cleansers containing Boron.
  • Distribute greywater evenly throughout the garden.
  • Install smart, simple and reliable systems
  • Everything sent through your pipes to the garden will absorb and benefit your landscape.
  • Rain water washes the soap down into the subsoil, preventing salt accumulation over many years.
  • Greywater for “tall” vegetables and fruit trees
  • The best vegetables are growing in; decaying compost, worm castings, animal fertilizer, bird droppings.
  • Body oils and dead skin actually enrich soil with microbes and beneficial bacteria.

Greywater Solutions

Simple Greywater Systems

Simple low cost and highly effective

Simple Greywater Systems

Laundry to Landscape

Branched drain system

The laundry to landscape system is of the simplest, most cost effective ways to reuse water. This system moves water from the washing machine out to the yard. Most effective on fruit trees, perennials, and some vegetables.

 A laundry to landscape system utilizes the washing machine pump to push water out to your garden. This irrigation method relies on gravity and the strength of your wash machines motor. It does not require filters or extra pumps which makes it a very low energy, low maintenance and effective approach.

Branched drain

In a branched drain greywater system the greywater from the house drains through a series of branching pipes and is dispersed into the landscape into mulch basin outlets. Showers, sinks and laundry can individually drain into the landscape, or be collected together into a single branched drain system. Typically branched drain systems are installed on showers, and a laundry to landscape system is installed on the washing machine. The greywater irrigation zone must be downhill relative to the shower, sinks and laundry inside the home. The branch drain is very time consuming to install. Each pipe has to be trenched and set at a perfect slope for gravity to equal distribution and direct the water.

Why should I install a “Laundry to Landscape” System?

This simple system is low cost, low maintenance, quick to install, and offers great flexibility. This is a great start for a low budget greywater system.

What is a simple “Branched drain” System?

Utilizing gravity, greywater flows horizontally through 1 1/2″ pipe at a constant 2% slope. Trenches are dug and the pipe is hard plumbed with no freedom to move. The water flow splits equally, distributing small quantities to each mulch basin. Strategically placed to irrigate the root zone of trees or other large perennials. Branched drain systems are time consuming to install(2-4days). They require very little maintenance and work well for the long term as no moving parts need replacement nor maintenance. The motorized three way valve assures freedom between the sewer and the landscape.

How does this Simple L2L System work?

The laundry machine pump diverts the greywater into the landscape through underground 1” flex piping. Equally distributing the water within outlet boxes, under mulch at the drip line of shrubs and trees.

How many plants / what type of plants can I water?

Depending on your washing machines gallon capacity(front loader = 15-20~, top loader = 30-45~). Typically 10-15 shrubs and trees can be satisfied with a simple L2L Greywater System. Because laundry water is dispersed into underground outlet boxes, the system cannot be used with spray lawn irrigation, and will provide too much water to smaller perennial and shrub plants. Refer to the General Greywater FAQ for information on plant types.

How much water can this system really save?

California Plumbing code states that each an average occupant produces 14 gallons of laundry water per day. Todays american household of 4 can produce up to 18,600 gallons of laundry water per year. A commodity well worth your landscapes investment.

Can’t I add my shower water to this system?

No! The laundry machine pump is used to move the water into the landscape and other house fixtures cannot be added to this system. In some cases a discharge tank and effluent pump may satisfy uphill and far applications. See our Integrated Greywater Systems for whole house options.

How much maintenance is really needed?

Not much! Every so often you should check the outlet boxes while the laundry machine is running to ensure water is sufficient as first installed. Palo Alto builders offers annual maintenance contracts to ensure system longevity.

Should I get a permit?

A permitted system adds property value as, prestige and notoriety for greywater continues to grow. Permitted systems ensure that all components and procedures are up to state codes and comply with local safety measures. Local authorities are helping to expedite the process making permitted simple systems easier to achieve.

Integrated Greywater Systems

Integrated Greywater Systems

Completely automated irrigation controlled operation. Ideal for renovation or new home construction. With, automatic municipal water backup. Greywater is filtered, then pumped throughout the landscape in a seperate drip irrigation line.

Why should I install an Integrated Greywater System?

The Integrated Greywater System is automated delivering filtered greywater to landscape through drip irrigation, with automatic municipal water for backup. It operates the same as a traditional irrigation system, but ideal for renovation, new home build, single fixtures and outlets.

I am not renovating my home. Can I install the Integrated Greywater System?

Every situation is site specific. Each home is unique plumbing system, and will need to be evaluated to assess the feasibility of installing such a Integrated System. The greywater system can easily be tied into the new home or renovation of the bathrooms being changed and redesigned.

How does the Integrated Greywater System work?

Greywater from the laundry, showers and bathroom sinks drains to a below or above ground tank (250-300 gallons). When the irrigation controller starts watering, a submersible pump in the tank pumps the greywater through a filtration system before being dispersed into the landscape through drip irrigation tubing. If no greywater is available in the tank, the system automatically supplies city water to the drip tubing. The filtration system is automatically cleaned, so maintenance is required only once per year.

How many plants / what type of plants can I water?

You can water as many plants as greywater is produced. However greywater cannot be used with spray irrigation and must be applied through subterranean drip tubing. Please see our General Greywater FAQ for more information on types of plants.

How much water will the system save?

California Plumbing code states that an average occupant produces 45 gallons per day from high efficiency showers, sinks and laundry. A typical american family of 4 will produce 60,480 gallons of grey water per year. A commodity well worth your landscapes investment.

I already have a drip irrigation system. Can I add on the Integrated Greywater System?

Yes, in most cases. California requires that the drip tubing be buried 3” under soil or mulch so some additional work on the irrigation system is required.

How much maintenance is needed?

Not much! We recommend a general systems check once per year, the greywater tank bag filter be replaced once every 2 years, and the greywater tank sediment removed once every 3 years. Palo Alto Builders offers annual maintenance contracts to ensure longevity.

Do I need a permit?

Although some states allow “simple” systems to be installed without a permit (our Simple Greywater System, for example), you will most likely need a permit to install the Integrated Greywater System.

Rain Catchment Systems

Rain catchement Systems

If the rain water simply runs off of your property, you’re not getting the full benefit of all that moisture!

A one-inch rain will collect 600 gallons from a 1,000 square foot roof and a 4,500 square foot lot will receive 2,800 gallons!

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