R317-401-5. Design of Graywater Systems

(a) The basis of design for a graywater system shall be as follows:

TABLE 1

Basis of Design

Number of Bedrooms Flow, gallons per day

Minimum two bedrooms 120

Three bedrooms 160

Each additional bedroom 40

(b) No graywater system or part thereof shall be located at any point having less than the minimum distances indicated as follows:

TABLE 2

Separation Distances

Minimum Horizontal Surge Tank Subsurface or

Distance (in feet) From Drip Irriga-

                                              tion Field

Buildings or Structures (1) 5 feet (2) 2 feet

Property line adjoining private

  property 5 feet 5 feet

Public Drinking Water Sources (3) (4) (4)

Non-public Drinking Water

  Sources

  Protected (grouted)source 50 feet 100 feet

  Unprotected (ungrouted)source 50 feet(5) 200 feet(5)

Streams, ditches and lakes (3) 25 feet 100 feet(6)

Seepage pits 5 feet 10 feet

Absorption System and

  replacement area 5 feet 10 feet

Septic tank none 5 feet

Culinary water supply line 10 feet 10 feet(7)

Footnotes:

(1) Including porches and steps, whether covered or

uncovered, but does not include carports, covered walks,

driveways and similar structures.

(2) For above ground tanks the local health department may

allow less than five feet separation.

(3) As defined in R309

(4) Recommended separation distances will comply with the

Source Water Protection requirements R309-600 and 605.

(5) Recommended separation distance may increase at the

discretion of the local health department for adequate public

health protection.

(6) Lining or enclosing watercourse or location above

irrigation area may justify reduced separation at the

discretion of the local health department.

(7) For parallel construction or for crossing requires an

approval of the local health department.

(c) Surge Tank

(i) Plans for surge tanks shall include dimensions, structural, bracing and connection details, and a certification of structural suitability for the intended installation from the manufacturer.

(ii) Surge tanks shall be:

(A) at least 250 gallons in volumetric capacity to provide settling of solids, accumulation of sludge and scum unless justified with a mass balance of inflow and outflow and type of distribution for irrigation;

(B) vented to the surface with a locking, gasketed access opening, or approved equivalent, to allow for inspection and cleaning;

(C) constructed of structurally durable materials to withstand all expected physical forces, and not subject to excessive corrosion or decay;

(D) watertight;

(E) anchored against overturning;

(F) installed below ground on dry, level, well compacted soil; in a dry well on compacted soil; or above ground on a level, four-inch thick concrete slab;

(G) Permanently marked showing the rated capacity, and "GRAYWATER IRRIGATION SYSTEM, DANGER - UNSAFE WATER" on the unit;

(H) provided with an overflow pipe:

(I) of diameter at least equal to that of the inlet pipe diameter;

(II) connected permanently to sanitary sewer or to septic tank; and

(III) equipped with a check valve, not a shut-off valve - to prevent backflow from sewer or septic tank.

(I) provided with a drain pipe of diameter at least equal to that of the inlet pipe diameter;

(J) provided with a vent pipe in conformance with the requirements of the International Plumbing Code; and

(K) provided with unions and fittings for all piping in conformance with the requirements of the International Plumbing Code.

(d) Valves and Piping

(i) Graywater piping discharging into a surge tank or having a direct connection to a sanitary drain or sewer piping shall be downstream of an approved water seal type trap(s) If no such trap(s) exists, an approved vented running trap shall be installed upstream of the connection to protect the building from any possible waste or sewer gases.

(ii) Vents and venting shall meet the requirements of the International Plumbing Code.

(iii) All graywater piping shall be marked or shall have a continuous tape marked with the words: DANGER - UNSAFE WATER.

(iv) All valves, including the three-way valve, shall be readily accessible.

(v) The design shall include necessary types of valves for isolation storage tank, irrigation zones and connection to a sanitary sewer or an onsite wastewater system.