Quick Facts...
- Graywater reuse may not be a permissible use of water under a domestic
well permit or a community water supply system.
- Rainwater harvesting is the process of intercepting storm-water runoff
and putting it to beneficial use.
- The diversion and use of rainwater is subject to Colorado water law,
making it difficult to use without a plan for augmentation that replaces
depletions to surface water flows. In most areas of Colorado, the most
common way to use rainwater is to direct roof gutter downspouts to landscape
areas you wish to water.
Graywater Systems
Graywater refers to the reuse of water drained from baths, showers, washing
machines, and sinks (household wastewater excluding toilet wastes) for
irrigation and other water conservation applications. Contrary to common
belief, graywater is not a “safe” product—it contains bacteria
and other potential pathogens. Consequently, the potential reuse of graywater
is a public health issue, not a water conservation priority.
Graywater is of lesser quality than tap water, but generally of higher
quality than blackwater, or water from sewage systems. Water from the
kitchen sink, garbage disposal and dishwasher is considered blackwater
in other states because of high concentrations of organic waste and the
difficulties of reusing this water safely.
The most obvious advantage of domestic graywater use is that it may potentially
replace other water used for landscape irrigation. Filtered graywater
is most suitably used for subsurface irrigation of nonedible landscape
plants. Not only does its use on landscapes conserve treated tap water,
but graywater may also benefit plants because it often contains nutrients
such as nitrogen or phosphorus.
Graywater use may offer financial savings to already overburdened municipal
sewage treatment facilities because graywater use diminishes sewer flows,
thereby lessening the need to expand such facilities. However, diminished
sewer flows may have a downside because graywater use can result in insufficient
sewer flows to carry waste to the sewer plant. Another concern is that
with increased use of graywater, less effluent water will be available
for treatment, resulting in less reclaimed water for municipal uses and
downstream appropriators.
Graywater systems vary from simple, low-cost systems to highly complex
and costly systems. A common (but illegal in Colorado and most other states)
method for reusing graywater is to drain the washing machine directly
onto outside vegetation. Sophisticated systems treat graywater prior to
disposal using settling tanks and sand filters in order to remove pollutants
and pathogens.
Graywater is different from warm-up water (wasted tap water that is allowed
to run down the drain before it reaches a desired temperature). Warm-up
water that has not been used for bathing or dishwashing is generally free
from bacteria and other pathogens. The amount of wasted warm-up water
can be significant in homes where water heaters are located a considerable
distance from showers or tubs and where no recirculation system is installed.
Catching this water in a bucket and using it to water plants can contribute
to home water conservation savings.
Water Quality Issues Surrounding Graywater Reuse in Colorado
Practically speaking, the use of graywater systems is not viable for
most homeowners in Colorado. Currently graywater is regulated under the
State of Colorado Guidelines on Individual Sewage Disposal Systems and
applicable county Individual Sewage Disposal System (ISDS) regulations.
The Colorado Department of Public Health and Environment (CDPHE) does
not currently separate graywater from blackwater in its regulations. Consequently,
both surface and subsurface applications require permitting and may trigger
monitoring requirements.
If graywater is discharged in the soil below the root zone in the manner
of a leach field, a permit from the local Health Department is required.
Your local county Health or Planning Department will have specifications
for adequate soil cover for leach fields that amounts to a minimum of
18 to 24 inches of soil cover. However, this deep application of the graywater
will not meet the practical needs of most homeowners, unless they want
to install a windbreak of trees or large shrubs. If graywater is used
to irrigate below the soil surface, but within the root zone (above frost
line), a local permit plus monitoring is required.
If the graywater is applied to the surface, a means of disinfecting the
graywater is necessary. Bacteria and other fecal borne pathogens in graywater
are a concern and may require installation of advanced treatment systems.
If estimations of graywater volume or soil intake rates are inaccurate,
ponding or runoff can become a problem. Graywater may also contain sodium
and chloride, which can be harmful to sensitive plant species. Research
on the public health hazards of graywater use is limited, with no data
indicating problems, or non-problems, for that matter.
Application of graywater from systems that discharge 2,000 gallons or
more per day requires a permit from the Colorado Department of Public
Health and Environment; smaller systems require permits from your local
health department.
Municipal Applications: A graywater system is defined as a type
of individual sewage disposal system that requires the owner to secure
an installation permit from the local county Health Department prior to
construction. Many county ISDS regulations prohibit the issuance of any
type of individual sewage disposal system permit for a lot within 400
feet of service by a municipal or community sewage treatment facility.
Many municipalities have similar connection and usage requirements that
technically prohibit the use of graywater in urban areas.
Rural Applications: On properties served by a permitted ISDS,
a request to install a graywater system should be submitted to your local
county Health Department. Many counties require the following criteria
to permit a graywater system:
- The system must be designed by a registered professional engineer.
- The graywater plumbing system collection lines must be segregated
from the blackwater (toilet) lines and must be a maximum of 2 inches
in diameter.
- The graywater system design must meet all minimum design and construction
standards of ISDS (except tank sizing).
- A graywater system must incorporate a first stage treatment unit consisting
of a two-compartment septic tank (sized with a 30-hour detention time)
or an NSF (National Sanitation Foundation) approved filtration or aeration
tank unit.
- The graywater system design components must meet the minimum requirements
for vertical and horizontal separation distances as defined in ISDS
regulations.
• For normal permitting processes, the final disposal of the graywater
outflow must be to a subsurface absorption field meeting sizing, construction,
and siting requirements.
- Graywater systems designed for use via sprinkler irrigation, direct
surface application, or subsurface disposal to shallow soil depths must
be sampled at least weekly for applicable effluent limitations as contained
in the ISDS guidelines; the use of graywater for irrigation may also
be subject to water rights limitations (as regulated through the Colorado
Division of Water Resources) which should be confirmed prior to considering
graywater reuse of any kind.
Water Rights Issues Surrounding Graywater Reuse in Colorado
If considering a graywater system where the source of water is from a
well, other issues must be considered. Well permits are issued pursuant
to Colorado statutes. The Colorado Division of Water Resources regulates
well water permits to prevent well pumping from injuring other water users.
Graywater use may not be a permissible use of water under a well permit
and this must be clarified prior to installing a graywater system. In
some cases, the conditions of approval under which a permit was issued
would not prohibit the capture and use of graywater. In other cases, the
permit conditions would not allow it. Specifically, if the permit was
issued for ordinary household purposes inside a single-family dwelling,
with no outside uses, the capture and use of graywater for any use outside
the dwelling (including lawn and garden irrigation) would not be allowed.
Well permits that were issued in areas of the state where the stream
system is not over-appropriated may qualify for use of a graywater system.
Old wells that are unregistered and were constructed prior to laws being
enacted that required a well permit, may qualify for graywater systems
if the historical uses included lawn and garden irrigation and they can
be late registered pursuant to section 37-92-602(5), CRS (2002). For wells
operating under court-approved plans for augmentation, the terms and conditions
of the decrees entered would have to be evaluated to see whether or not
graywater systems would be allowed. In most cases, these plans for augmentation
rely in part on the return flows generated by the individual well. In
such cases, graywater systems might not be allowed.
Many of the permits issued throughout the state on parcels of land less
than 35 acres contain restrictions that disallow the use of graywater.
Permits issued on tracts of 35 acres or more with a return flow requirement
could possibly utilize a graywater system if it is demonstrated that the
actual depletion to the stream system was not increased.
Rainwater Harvesting
Rainwater harvesting is the process of intercepting storm-water runoff
and putting it to beneficial use. Rainwater is usually collected or harvested
from rooftops, concrete patios, driveways and other impervious surfaces.
Buildings and landscapes can be designed to maximize the amount of catchment
area, thereby increasing rainwater harvesting possibilities. Intercepted
water then can be collected, detained, retained and routed for use in
evaporative coolers, toilet flushing, pet and car washing, indoor plant
watering, pet and livestock watering, and for lawn and garden irrigation.
Rainwater harvesting systems vary from the simple and inexpensive to
the complex and very costly. Typically, these systems are simple, consisting
of gutters, downspouts, and storage containers. Directing rainfall to
plants located at low points is the simplest rainwater harvesting system.
In this system, the falling rain flows to areas with vegetation. Inexpensive
rainwater storage systems commonly make use of above ground containers
such as a barrel or plastic tank with a lid to reduce evaporation and
bar access for mosquito breeding. Any container capable of holding rain
dripping from roof or patio can be used as a rainwater harvesting system.
Water Quality Issues Concerning Rainwater Harvesting
Rain in urban and industrialized areas may contain various impurities
absorbed from the atmosphere, including arsenic and mercury. In Colorado,
rain is infrequent, but rainwater quality is generally very good. However,
the infrequency of rainfall results in accumulation of bird droppings,
dust and other impurities on rooftops between rain events. These impurities
may occur in high concentrations in rooftop runoff when it does rain.
The best strategy is to filter and screen out contaminants before they
enter the storage container. Dirty containers may become a health hazard
or a breeding ground for mosquitoes and other pests.
Various methods can be used to purify rainwater. First-flush devices
ensure a certain degree of water quality in harvested rainwater. The first
several gallons of runoff from a gutter, roof, or other surface are likely
to contain various impurities such as bird droppings and dust. A first-flush
device prevents this initial flow from draining into the storage tank.
Many first-flush devices have a simple design. Such devices include tipping
buckets that dump when water reaches a certain level. In addition, there
are containers with a ball that floats with the rising water to close
off an opening after an inflow of five gallons. Water is then diverted
to a pipe leading to the storage container. This use of simple technology
is an attractive feature of rainwater harvesting. Roof washing is not
needed for water used solely for irrigation purposes. However, pre-filtering
to keep out debris will reduce sediment buildup in the irrigation system.
Due to concerns surrounding microbial contamination of harvested rainwater,
it is not recommended as a source of drinking water for humans. However,
properly designed, constructed, and maintained systems that include disinfection
steps have been successfully used for private domestic water supplies.
Consult your local Health Department prior to constructing rainwater harvesting
systems.
Water Rights Issues Concerning Rainwater Harvesting
The diversion and use of rainwater is subject to the Constitution of
the State of Colorado, state statutes, and case law. New Colorado residents
should understand that water rights in Colorado are unique compared to
other parts of the country. The use of water in this state and other western
states is governed by what is known as the prior appropriation doctrine.
This system of water allocation controls who uses how much water, the
types of uses allowed, and when those waters can be used. A simplified
way to explain this system is often referred to as the priority system
or "first in time, first in right."
An appropriation is made when an individual physically takes water from
a stream or well (when legally available) and puts that water to beneficial
use. The first person to appropriate water and apply that water to use
has the first right to that water within a particular stream system. This
person, after receiving a court decree verifying their priority status,
then becomes the senior water right holder and that water right must be
satisfied before any other water rights are filled. In Colorado, the State
Engineer has the statutory obligation to protect all vested water rights.
The process of allocating water to various water users is traditionally
referred to as water rights administration, and is the responsibility
of the Division of Water Resources.
Of course, the appropriation system is much more complicated than described
above. Some priorities on major stream systems in Colorado date back to
the 1850's, and most of the stream systems have been over-appropriated,
meaning that at some or all times of the year, a call for water even by
a senior appropriator is not satisfied. Practically speaking, this means
that in most river drainages, a person cannot divert rainwater and put
it to a beneficial use without a plan for augmentation that replaces the
stream depletions associated with that diversion. In most areas of Colorado,
the only sure legal way to use rainwater is to direct roof gutter downspouts
to drain to landscape areas you wish to water.
It is recommended that before you develop a rainwater harvesting system
you check with the Colorado Division of Water Resources and your local
building, zoning, and environmental departments to determine what plumbing
requirements, local restrictions, neighborhood covenants, or other regulations
or guidelines might apply to your project. Rainwater catchments, distribution
systems, and landscape holding areas must be located and used entirely
within the property boundaries of the individual or entity building using
the system. These systems must be maintained in an acceptable manner and
not cause damage or interference to neighboring property. Standards for
construction must be consistent with industry standards or as determined
by the local administrative authority.
Additional Information
For more information, contact your local county Health or Planning department
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