Current through Register Vol. 24-18, September 15, 2024
(1) The following conditions and restrictions
apply to each Tier 1 greywater irrigation system:
(a) The greywater must be light
greywater.
(b) The total flow of
greywater must be sixty gallons per day or less.
(c) The greywater must originate from a
single-family residence.
(d) The
single-family residence must be served by an approved public sewer system or
on-site sewage system.
(e) The
greywater must be diverted to the subsurface irrigation system through a single
diversion point. Flows from fixtures located close enough to each other to be
diverted through a single diversion point may be combined.
(f) The greywater must be delivered through
the irrigation system by gravity distribution. Pumps may not be used to convey
the greywater.
(g) The greywater
may not be stored.
(h) The total
minimum irrigation area available to receive the greywater must be adequate
based on a calculation of:
(i) The estimated
volume of greywater;
(ii) The
evapotranspiration rate in inches per week for the geographic area of the state
where the landscape or garden is located; and
(iii) The water requirements of the plants,
known as a plant factor. A "Greywater System Checklist and Irrigation Area
Estimation Tool" is available from the Washington state department of health's
web site.
(i) The
greywater must be distributed throughout the irrigation area.
(j) The homeowner may direct greywater to
separate irrigation fields so long as the total flow of greywater to all fields
combined does not exceed sixty gallons per day.
(k) The Tier 1 system must be covered by at
least four inches of appropriate material which may include suitable soil or
other material such as mulch, humus, or compost. If material other than
suitable soil is used, the irrigation field cover must be augmented
periodically as needed to maintain adequate cover during the growing
season.
(l) The homeowner shall
ensure that the Tier 1 system is properly operated and maintained.
(m) The homeowner shall maintain a record of
the Tier 1 system that:
(i) Shows the
location of the system;
(ii)
Identifies the fixture(s) that are the source of the greywater;
(iii) Describes the system design and how it
meets the requirements of WAC
246-274-100;
(iv) Describes the system's maintenance
requirements; and
(v) Includes the
calculation of the total minimum irrigation area required under subsection (h)
of this section.
(n) The
homeowner shall maintain the record of the system on a completed "Greywater
System Checklist and Irrigation Area Estimation Tool."
(2) A homeowner may install and use a maximum
of two separate Tier 1 systems, with combined flows of one hundred twenty
gallons per day or less, to allow for reuse of greywater originating from two
separate diversion points. The total flow of greywater to the irrigation field
or fields used by each system must not exceed sixty gallons per day.
(3) The local health officer may require the
homeowner to register the Tier 1 greywater system(s) by filing the record,
required in subsection (1)(m) of this section, with the local health
jurisdiction. He or she may require additional review when two separate systems
are installed or if the property is served by an on-site sewage system with
design flows of less than three thousand five hundred gallons per
day.
(4) The owner shall comply
with any more stringent regulations adopted by the local health jurisdiction
including design and permitting requirements.
Statutory Authority: RCW 90.46.015. 11-02-011, §
246-274-100, filed 12/28/10, effective
7/31/11.
