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Different ways to reuse graywater (part 2)

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Gravity Dripperline, Pumped Dripperline, Buckets, Branched Drain, Laundry to Landscape

Gravity Dripperline (IrriGRAY)

IrriGRAY dripperline is special graywater dripperline that only requires 400 micron filtration (standard dripperline requires 4 times as much filtration). It has built in emitters every 12" and is connected to a main supply line with a punch tool and takeoff connectors.

The basic concept is to have the washing machine water flow into a temporary surge container, such as a 55 gallon barrel or trash can. Wtaer will irrigate at 1 gallon per minute per 150' of dripperline, even with only 12" of water in the container.

A 3/4" supply line is connected to the bottom of the container and run out into the garden areas. Where irrigaiton is required, the dripperline is connected to the supply line, in any number of independent segments, up to 60' long. The recommended maximum length of dripperline overall is 300', although 150' is most common.

There is a 4 minute video showing how to modify a container and install the IrriGRAY gravity dripperline kit, on our videos page.

Advantages:

  • Cost:

    Excluding the cost of the container, a basic kit can be purchased for approximately $240. (used food grade barrels can be found for around $20 in most areas)

  • Ease of installation / DIY installation

    Most irrigation systems can be laid out by two people in under 20 minutes. The barrel / container can be modified in 5 minutes. The dripperline irrigates evenly on flat or sloping ground (but will not flow uphill - it is a gravity system!)
  • Efficient & Even irrigation

    150' of Irrigray dripperline has 150 emitters, so graywater is spread evenly acorss the garden area. Because of this the irrigation efficiency is over 90%, so making the most of your graywater. Plant growth is also stronger, becuase the plant roots can spread far wider (the entire garden area is moist) and therefore have greater access to nutrients in the top 3" of soil.
  • Maintenance is limited to one location (the filter outside the base of the container). This filter will need cleaning approximately every 2 months (large filter fitted) or every week (small filter fitted)

Disadvantages:

  • Limited irrigation area

    The maximum amount of IrriGRAY dripperline that should be used is 300'.
  • Filter requires regular cleaning

    The small filter will need cleaning on a weekly basis. The optional large filter will need cleaning approximately every 2 months. Both filters are easy to clean, taking no more than 1 or 2 minutes to clean.
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Pumped Dripperline (IrriGRAY)

When a powerful dirtywater submersible pump (eg 660W) is used, graywater can be irrigated over large areas, close to and far from the pump with even drip rates across the whole area.

Because gravity is not an issue, the pump can be located at any depth, 42" below ground level is not uncommon. This allows all of the household graywater to be collected, if the plumbing is setup with separate graywater stubouts.

Advantages:

  • Capability to irrigate large areas, evenly

    Customers are re-using up to 10,000 gallons per month using the IrriGRAY pumping and irrigation systems, saving over 15,000 gallons of potable water per month (graywater irrigaiton is more efficient than potable water irrigation).
  • Improved garden growth

    The nutrient laden water, combined with even irrigation, allows strongth root growth within the biologically active topsoil. Gardens grow better with Graywater!
  • Maximum collection and reuse of graywater

    Because gravity is not an issue, the pump can be located at any depth, 42" below ground level is not uncommon. This allows all of the household graywater to be collected, if the plumbing is setup with separate graywater stubouts.
  • Best Long term Return on Investment

    Although a completed system may cost $2,000 or more fully installed, in most cases the water savings (and therefore sewerage charges savings as well) provide a payback period of 2-4 years.  Savings continue year after year.

Disadvantages:

  • Initial cost

    With a purchase price of around $1,000, plus installation costs of approximately $1,000 (the majority of which is plumbing cost - this decreases significantly for new homes), the establishment cost is higher than other methods.
  • Regular filter cleaning

    The large filter (standard with all  pumping systems) will need cleaning every month to two months (in most cases). The filter is easy to clean, requiring only 2 minutes per month. Other systems with very large filters are available, however because the filter is an integral part of the pumping container, can be very difficult to access, and in any case are cumbersome and time consuming to clean.
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Buckets

Buckets are cheap, and with care and effort can be used to water various areas of the garden.  Points to consider are:

  • Limited amount of water

    Most people only use 1 or 2 buckets in the shower. This will capture up to 4 gallons per person per day. Not enough for the whole garden (unless your balcony is the garden), but enough for prized plants.

    Note a 10 minute shower (the shower would need to run this long to fill the buckets), running at 3 gallons per minute is 30 gallons of water, so 26 gallons of water is used to save 4 gallons.

    The average person generates between 25 and 40 gallons of graywater per day in the shower, bath and laundry. So buckets are a great start, but only re-use about 10% of the graywater going down the drain.
  • Over watering

    During water rationing, people often concentrate on a limited number of prized plants. Always check the soil moisture level before adding extra water. Killing plants by over watering is a common problem in drought affected areas.
  • Safety

    Apart from back problems caused by frequent carrying of buckets in the house and in the garden, beware of spilled water / slipping dangers.
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Hoses


Washing Machines

About 5 years ago major Australian hardware chains started selling 1" hose kits. The kit couldn't be simpler, a 1" hose, with a rubber connection on one end and simply open at the other. People simply connected the hose to the washer, and moved the hose around the garden from wash to wash.
 
In addition to the high risk of blowing up washer machine pumps (see laundry to landscape), with simple hoses such as these, the following were particular problems in Australia:

  • Over watering / Under watering

    With simple hoses, all the water (often 40 gallons per wash) is dumped in one small area of the garden, resulting in over watering that area, with other areas going dry. Similar to bucket watering, people would concentrate water in their favorite areas, in the end killing with over watering.

 

  • Killing plants with high PH water

    To avoid over watering favorite garden areas, people would move the simple hose between wash / rinse cycles, 'sharing' the water around the garden during the wash.

    In theory this is fine. In practice  people develop a habit of always moving the hose around in the same pattern (eg. 1st water here, 1st rinse over there, and the 2nd rinse in the third spot). This is not good for your garden and will kill plants over time.

    The issue is primarily the first load of water from the washer machine. Virtually all effective washing powders, 'eco-friendly' or not, need high PH water to wash the dirt from the clothes. The PH of this first amount of water is 10.5. As the washer processes each cycle, the PH of the water in drops.

    If you were to temporarily store all of the water from one wash, the overall PH is generally between 9.0 and 9.5 which is ok for most gardens.

    Always watering in one area with PH 10.5 water will kill plants. If you are going to move a hose around, move in a different pattern each day.


Waste Pipe Diverters / Hoses
         
These diverters come in many shapes and styles. They divert water from showers (pipe under the house) and laundry (often a vertical pipe on the outside wall). Gravity hoses can then be connected to the diverter valve.

Although shower water is basically PH neutral, and therefore removes PH risk, over watering becomes a significant issue, especially when diverting all shower water, and not moving the hose each day.
        
Over watering remains a significant risk for laundry pipe diverter and hose sets. A more sophisticated diversion system is the Branched Drain Network.

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Branched Drain (or similar)

The basic concept is to allow the graywater to flow from the house by gravity alone, typically through 2" pipes. To distribute the water into more than one location, a double Ell (a sepcial type of T fitting) is used to split the flow into two. More double Ells can be used to split the flow further.

Theoretically the flow could be broken into 16 or more directions, although 8 is about the practical limit for a typical household (beyond this the pipes and Ells are too senstive to water flow and uneven distribution would occur.)

Advantages:

  • Low material cost.

    Many small networks can be made with just $100 worth of materials. Larger systems may cost $400+ worth of materials.

  • Relatively low maintenance

    Apart from keeping a good layer of mulch in the mulch basins, the only maintenance required is a monthly check of the double Ell's (removing a plug to inspect and clean if necessary).

Disadvantages:

  • Very Low water efficiency, typically the lowest efficiency of any water reuse method. Almost all of the graywater passes through the soil into the subsoil beneath the plant / tree root layer. If this method must be used, trees would be the best candidate.  Keep in mind the tree roots will concentrate in the mulch basin, and will not spread far from the base of the tree. Additional feeding (fertilizer) will be required due to the lack root growth.

  • High labor effort. This method is exacting. The 2" pipes must run to grade (approximately 2%) so that water splits properly at the Ell's. Each Ell must be positioned exactly level to ensure even splitting of the water flow.

Before considering a mulched drain system, we strongly recommend viewing the mulch basin video on our videos page. This 8 minute video illustrates the work and attention to detail required.
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Laundry to Landscape

Laundry to Landscape is a washing machine pressurized irrigation method, popularized in California.

The basic concept is connecting a 1" or larger hose connected to the outlet of the washer machine, and running this hose as long as required to reach the irrigation area. Adjustable valves are then added to allow the graywater to empty into mulch basins around trees and plants.

Advantages:

  • Cost.

    This method is relatively low in cost, typically $200+ for materials, + labor. The irrigation layout is also less demanding than the branched drain network.

Disadvantages:

  • Washer machine pumps are NOT built for this.

    Plumbers and appliance stores have made a LOT of money in Australia either repairing or replacing washing machines.

    About 5 years ago major hardware chains started selling 1" hose kits. The kit couldn't be simpler, a 1" hose, with a rubber connection on one end and simply open at the other. People simply connected the hose to the washer, and moved the hose around the garden from wash to wash.

    Even with a totally open hose (in most cases 30' long), many washer machines failed within 3 years use. Pressurizing the washer machine pump by restricting the flow via valves etc places even more load on the pump.

    A far better (and now common) approach in Australia is collecting the graywater in a barrel like container, and using a automatic pump to force the water to the irrigation area (whether using a dripperline system, spray nozzle or sprinkler, subject to the water type and local regulations), or using gravity dripperline to simply allow the water to empty out of barrel at approximately 1 gallon per minute.     
  • Uneven flow rate across irrigation points.

    The water pressure inside the pipe at each irrigation point will vary according to the flow rate at each point, the distance of the point from the washer machine, and how much water the washer machine is pumping out at any one time.

    Much time and effort is required to tune numerous valves to achieve consistent, even irrigation.
  • Lack of filtration causes clogging.

    Washer machines can produce a significant amount of lint and hair. This rapidly clogs any pressurized irrigation system unless additional filtration is used. A simple but reckless solution is to place a filter sock (or similar) on the washer machine outlet. However this places even more load on the washer pump.

    An alternative method is to use large holes in the irrigation tube. The large holes won't clog as easily, however tuning such systems to water more than one area takes trial and error to achieve even watering.
  • Reliance on Mulch basins.

    Because of the relatively limited number of outlets, mulch basins are required to catch the sudden flow of water. As with branched drain networks (although not to the same extent as it is easier to create more basins with Laundry to Landscape), this method is really only suited to trees, and the trees will still require extra feeding due to the limited root growth that will occur.

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