Greywater Wetlands

Greywater is wastewater collected from domestic activities such as, sinks, laundry, showers, and bathtubs, not from toilets. Greywater can be recycled and used to water non-consumables and to develop constructed wetlands. However, greywater may not be used to irrigate consumables, such as vegetable gardens, fruit trees, etc.

The photos below depict a greywater wetland. The homeowner had a failing septic field but intended to build a new house.  The septic field would have been temporary as the new house was going to be built some distance away.  By reducing hydraulic flows to the old, failing septic field, it recovered independently making a replacement no longer necessary.

constructed-wetland-1

A greywater wetland that saved building a new septic system

 

constructed-wetland-2

A greywater wetland designed and built by WetlandsPacific Corp. in 2003

 

constructed-wetland-3

WetlandsPacific builds greywater wetlands that do not have open water

 

 

Questions and answers about greywater

What is “Greywater”?

Water (and wastes) from sinks, laundry, showers, and bathtubs but not from toilets.

What is “Blackwater”?

Water (and wastes) from toilets.

Does the public health regulation differentiate between the two?

Under the B.C. Sewerage System Regulation (SSR) of British Columbia, both greywater and blackwater are domestic sewage, period. 

What are the B.C. Regulations concerning Greywater?

The Sewerage System Regulation (SSR) does not differentiate between greywater & blackwater.

Do I need a health permit for greywater system?

Definitely yes.  As the current Standard Practice Manual (SPM) does not mention greywater systems, the safest way to proceed is with the assistance of a wastewater professional.  WetlandsPacific employs and works with professionals.

Are composting toilets legal in BC?

Yes and maybe.  Many B.C. highway rest stops are served by composting toilets and the SSR does not come into effect until outside the dwelling so it is up to the local plumbing code.

What are the options for treating greywater?

At a minimum you will need to have tankage that will function as a septic tank to liquefy solids, a way to further treat the effluent to remove the possibly many remaining contaminants, and a place to disperse the effluent subsurface in a manner that does not constitute a public health hazard.

Does WetlandsPacific design and build greywater wetlands?

Yes, we built the first one in 2003.

Are constructed wetlands for greywater legal in B.C.?

While not specifically mentioned in the code, a wetland pond that is constructed and operated so as to not cause a health hazard scenario as described in Section 2.1 of the SSR, would not be in conflict with the regulation.   

What does WetlandsPacific recommend for treatment and dispersal?

We recommend using a constructed wetland system specifically designed for your property and flows as they not only remove the contaminants we measure, but also the ones we do not.

If we install a composting toilet and a greywater wetland will we have to provide special care?

Yes, source control must be practiced.  All of the solid wastes that are not human wastes should be diverted to a waste stream that ends up in a landfill such as via a garbage can.  Liquid wastes such as mop bucket water should be directly poured on vegetation.

Will there be any open water in my greywater wetland as designed by WetlandsPacific?

No, as we neither wish to have wetlands lumped in with lagoons, nor be inconsistent with public health standards.

My wife and I have an older home with a septic field that is wet and spongy but we don’t want to put a new tank and field in as we are building another home on our property that can’t be tied into where a replacement field would have to go.  What are our options?

It is against B.C. health regulations to have sewage surfacing in your yard so you have to fix it.  You have several options:
•    First check to make sure none of your plumbing fixtures are leaking by placing food coloring in the tank, if any shows up in the bowl, the leak should be fixed.
•    Add a Nayadic treatment plant with the idea of moving it once new house is built.
•    Is your plumbing accessible?  If so you could divert your greywater to a new septic tank and add a greywater constructed wetland for considerably lower cost than a new septic system.  That would allow your existing field to dry up.
•    There are a number of other options, depending upon your specific circumstances.  Contact WetlandsPacific to arrange for our certified personnel to make a site visit to your property.  They can explore with you the options you have to choose from.  

Can we grow food crops in treated greywater?

Without testing for each and every contaminant that may be present in greywater it is inadvisable.  A better bet for irrigation is rainwater harvesting.

What is a Greywater Wetland?

Greywater wetlands come in many variations.  Some use gravel, which is very difficult to deal with once plugging occurs, others have open water.  You are not likely to want that either as open water could be classified as a lagoon and so require very large setbacks from property lines, wells, and dwellings. A constructed wetland can be the perfect way to insure whatever contaminants have been introduced by human use are reduced to a level where it is environmentally safe to wick into soil, consequently cannot create public health issues.  

Can we irrigate non-food vegetation with greywater wetland treated water?

Yes, but only in accordance with the SSR, which requires wastewater to remain subsurface.  Plus the wetland must be specifically designed for that purpose otherwise there may not be any water left after the wetland pond.

How Does WetlandsPacific Design Your Wetland?

Usually we start with a site visit to gather information on what specifically you are seeking as well as on your particular property:
•    Size of your home so we can determine flows.
•    Your thoughts on location.
•    What you want the overall appearance to be (manicured garden to blending into background vegetation).
•    Types of plants you wan (ornamental or native species that blend in).
•    Construction and planting timing.
•    Permitting issues.
•    What portion of the several tasks involved, if any, you wish to do.

How specifically are greywater constructed wetlands designed?

First the wastewater needs to have pretreatment in a tank with sufficient retention time to liquefy solids and dissipate toxins.  That insures the most reactive substances such as bleach and antimicrobial soaps are either react or are diluted.  Then the effluent is generally piped into a wetland.  As WetlandsPacific designs and builds wetlands according to the highest standards of environmental protection the first area or first pond(s) have impervious bottoms and side walls to insure a lengthy retention time.  It takes surface area for microbial attachment and time to allow the aquatic community to break down or absorb contaminants.

What is a wetland?

Wetlands have three characteristics:
1.    Water level is at or near surface for at least part of the year.
2.    Hydric soils (peaty, high organic content, low sand or gravel that remain wet for most of the year).
3.    Contain facultative or obligate aquatic vegetation.


Does WetlandsPacific design gravel-based wetlands?

No, as they are not by definition wetlands, have a much, much lower specific surface area, so occupy a significantly larger area so cost more, plus they were devised for wastewater in the southern U.S. where warmer temperatures keep organic material from plugging up gravel.  

How much of our domestic water use ends up as greywater?

About 70-75% of the water entering an average dwelling.  That does not count water used outside.  Another way of estimating flows is Canadians use about 600 L (130 ig) each per day, which includes outside uses such as irrigation.  So if you have 4 persons in your household chances are you are using about 2400L (500 ig) on a yearly average.  Separating out the outside usage Canadians use about 230 L-day (50 ig-day) per capita of which about 170 L (35 ig) is greywater.

How much can we save on our water bill by reusing greywater?

While water prices vary with locations, for the Victoria area potable water costs about $1.50/m3, which includes the flat fee plus usage charge assuming 300 m3-yr usage.  Outside of a greenhouse, irrigation is usually not necessary from November – February, which is 4 months or 1/3rd of the year.  So 300m3 used per year x 75% as greywater x 67% of the year when watering is needed x $1.50 m3 = $226 per year saved on water bill.  With watering restrictions and the uncertainty global climate change brings greywater reuse into the realm of at least being desirable.  (Rainwater harvesting should also be considered.)  There is also a benefit to the community in that more water supply capacity does not have to be built at the cost of tens or even hundreds of millions of dollars, and storm water runoff is reduced thus saving construction and operational costs of storm water collection, treatment, and dispersal.

Source:  http://www.crd.bc.ca/water/waterbilling/ratecomparison.htm