Chapter 19D.130


19D.130.010    Purpose. Amended Ord. 2021-47s

19D.130.020    Definitions. Amended Ord. 2021-47s

19D.130.030    Applicability. Amended Ord. 2021-47s

19D.130.040    General Provisions. Amended Ord. 2021-47s

19D.130.050    Specific Provisions. Amended Ord. 2021-47s

19D.130.060    Standards Review Subcommittee. Amended Ord. 2021-47s

19D.130.070    Severability. Amended Ord. 2021-47s

19D.130.010 Purpose. Amended Ord. 2021-47s

The purpose of this Regulation is to establish minimum standards of water system planning, design, and construction for all new or expanding public water systems or improvements in existing water systems in Pierce County. These Regulations are intended to be used in the implementation of the Pierce County Coordinated Water System Plan. (Ord. 96-92S § 1 (part), 1996; Ord. 96-111 §§ 2, 8 (part), 1996; Ord. 94-82S § 3 (part), 1994)

19D.130.020 Definitions. Amended Ord. 2021-47s

The definition of terms shall be as used in the Pierce County Coordinated Water System Plan and as adopted by the State of Washington, Department of Health (DOH), Public Water Supply Regulations. (Ord. 96-92S § 1 (part), 1996; Ord. 96-111 §§ 2, 8 (part), 1996; Ord. 94-82S § 3 (part), 1994)

19D.130.030 Applicability. Amended Ord. 2021-47s

A.    General. These Regulations shall apply to all new and expanding public water systems or improvements to existing systems in Pierce County. The water purveyor may adopt more stringent regulations for the design and construction of water systems in the water purveyor's designated water service area, provided said service area is approved by the Department of Health and by the Pierce County Department of Planning and Public Works (PPW).

B.    Utility Plans and County Land Use Plan. The design standards are intended to establish minimum levels of service to be planned by water purveyors for different land use designations. Land use designations shall be those identified in the adopted Pierce County Comprehensive Land Use Plan and implementation ordinances.

The purveyor shall prepare a plan and a program of capital improvements required to provide the anticipated level of service in each land use area. When the purveyor is requested to provide water service, it will identify that portion of planned capital facilities, as well as other installations, which are necessary to provide the service requested. As growth occurs, the full level of water service will eventually be provided throughout the service area of the purveyor in a planned, phased program which meets County requirements and minimizes overall cost to the customers.

The minimum standards described herein do not apply to municipalities insofar as service within corporate boundaries is concerned. However, it is expected that municipalities will adopt (or have adopted) design standards as least equal to those herein. If municipalities extend new water service to customers outside of the city limits, the design standards adopted by the municipality for outside-city service must at least meet these minimum standards.

C.    Design Standards in Rural Areas. Water purveyor planning and facility design in rural areas must seek a level of service which is consistent with realistic expectation of development in these areas. In many areas, a density of development which justifies large scale facilities may not be likely.

The minimum design requirements in rural areas are such that a greater burden of water supply planning is site-specific. Public water purveyors serving low density rural residential areas are expected to plan only domestic water service. An individual or developer who proposes other land uses in rural areas is responsible for identifying additional water needs for the proposed development, and shall then enter into an agreement with a purveyor or SSMA if some or all of those needs must be met by the public water system.

In those rural areas where zoning is such that there may be non-residential development, or residential development with density exceeding an average of one unit per gross acre (net lot size less than 35,000 square feet), a water purveyor's expansion plans shall be designed based at least on providing fire flow in a phased development program. Fire flow requirements are contained in Pierce County Code Chapters 15.12 and 15.40.

(Ord. 2017-12s § 2 (part), 2017; Ord. 96-92S § 1 (part), 1996; Ord. 96-111 §§ 2, 8 (part), 1996; Ord. 94-82S § 3 (part), 1994)

19D.130.040 General Provisions.

A.    Source Development. New sources must be designed to meet the State of Washington, Department of Ecology (DOE) and the Department of Health (DOH) regulations and design guidelines including WAC 173-160, Minimum Standards for Construction and Maintenance of Water Wells, administered by DOE, and WAC 246-290 and 246-293, "Rules and Regulations of the State Board of Health Regarding Public Water System", as administered by DOH.

B.    Water Rights. Water rights must be obtained in accordance with DOE regulations and procedures, and copies of water right documents, correspondence, and other records are to be maintained on file with the purveyor.

C.    Water Quality. Water quality must be proven to conform with DOH criteria specified in WAC 246-290 and 246-293 and/or any additional requirements more stringently applied by the local health department.

D.    General Design Specifications. Except as otherwise superseded in these standards, water system design, installation, modification, and operation, is subject to the "Rules and Regulations of the State Board of Health Regarding Public Water Systems," WAC 246-290.

E.    General Material Specifications and Construction Standards. Except as provided in approved plans and specifications, or in these minimum standards, selection of materials and construction of water system facilities in Pierce County shall conform to the following:


1.    Applicable County or Municipal ordinance,

2.    "Standard Specifications for Road, Bridge, and Municipal Construction", Washington State Department of Transportation as amended by APWA, Most Recent Edition (DOT/APWA),

3.    Standards of the American Water Works Association (AWWA),

4.    Polyvinyl-Chloride pipe meeting the requirements of ASTM 2241 with a maximum standard dimension ration of 21.


1.    Applicable County or municipal ordinance(s), and, if applicable,

2.    "Standard Specifications for Road, Bridge, and Municipal Construction", Washington State Department of Transportation APWA, Most Current Edition (DOT/APWA), or

3.    Standards of the American Water Works Association (AWWA).

Along County road rights-of-way in unincorporated areas, a County utility permit must be applied for and approved by the County prior to construction. Construction within incorporated areas remains subject to municipal permitting requirements. All requirements of the permit shall become part of these specifications.

F.    Hydrostatic Pressure Test. A hydrostatic pressure leakage test shall be conducted on all newly constructed or repaired water mains, fire lines, fire hydrant leads and stub-outs in accordance with DOT/APWA Section 7-11.3(11) or AWWA C-600 specifications.

G.    Disinfection and Bacteriological Testing. All pipe, reservoirs, and appurtenances shall be flushed and disinfected in accordance with the standards of the Washington State Department of Health (DOH) WAC 246-290 and 293.

H.    Auxiliary Power and Emergency Planning. All sources and booster pumping facilities required for maintaining an average day supply of water in an emergency should be equipped with auxiliary power or with power pigtail and manual transfer switching devices. Contingency plans for providing water during emergency situations shall be included in individual water system plans.

I.    Utility Interties. When planning for system improvements or extensions, specific locations, size, and alignment of major water lines, a purveyor shall incorporate consideration and coordination of emergency interties with adjacent water purveyors.

J.    Flow Measurement. All service lines shall be installed so that each residential, commercial, and industrial structure will have a separate metered service for domestic water received from the purveyor. If approved by the designated purveyor, domestic water consumption may be measured by a master meter for service to a complex, under single ownership, and where water utility line subdivision is impractical. Service lines providing fire flow may be required by the purveyor to be equipped with detector meter.

All new groundwater sources shall be provided with device for measurement of depth to water and total production. Installation of these devices is also recommended for existing groundwater sources. All new sources for which water treatment is included shall be provided with flow measurement devices.

K.    Cross Connection Control. Where the possibility of contamination of the supply exists, water services shall be equipped with appropriate cross connection control devices in accordance with WAC 246-290 and 246-293. The designated purveyor shall determine the need, size, kind, and location of the cross-connection control devices following the specifications in the Uniform Plumbing Code and the most current edition of the Cross-Connection Control Manual by the Pacific Northwest Section of AWWA.

(Ord. 96-92S § 1 (part), 1996; Ord. 96-111 §§ 2, 8 (part), 1996; Ord. 94-82S § 3 (part), 1994)

19D.130.050 Specific Provisions. Amended Ord. 2021-47s

A.    Pressure Requirement. Water systems shall be designed to maintain a minimum residual pressure of 30 psi in water mains under maximum demand flow conditions, excluding fire demand. For water systems requiring fire flow capability, the design shall be adequate to maintain, under fire flow conditions, positive pressure throughout the system and a 20 psi residual pressure in mains supplying fire hydrants in use (c.f. WAC 246-290).

B.    Pipe Sizing. Water mains shall be sized using the current edition of "Sizing Guidelines for Public Water Supplies," prepared by the State of Washington, Department of Health (DOH). For sizes six inches and above, minimum main size may be established by a licensed engineer using recognized hydraulic analysis techniques. Water main size shall be adequate to deliver fire flow, if required, and to maintain the pressure requirement defined above.

When fire flow is required, refer to Chapter 15.40 of the Pierce County Code for pipe sizing specifications.

C.    Isolation Valving. Valving shall be installed in a configuration which permits isolation of lines. A valve is not generally required for short block lines of less than 100 feet. In addition, unvalved lengths of pipe serving commercial, multi-family or school areas, should not exceed 400 feet.

D.    Air and Air-Vacuum Relief Valves. In order to minimize problems associated with air entrainment, the purveyor shall provide for installation of air or combined air-vacuum relief valves at appropriate points of high elevation in the system.

E.    Blow-off Valves. A blow-off assembly shall be installed on all dead end runs and at designated points of low elevation within the distribution system. The blow-off assembly shall be installed in the utility right-of-way except where an access and construction easement is provided for in writing by the water purveyor. In no case shall the location be such that there is a possibility of back-siphonage into the distribution system.

F.    Storage. Storage requirements are based upon three components;

1.    Equalizing Storage, required to supplement production from water sources during high demand periods,

2.    Standby Storage, required as backup supply in case the largest source is out of service, and

3.    Fire Storage, required in order to deliver the level of fire flow service identified in the purveyor's approved plan.

Sizing of storage facilities shall be adequate to provide for equalizing storage plus the larger of standby or fire storage requirements. Equalizing and standby storage volumes shall be determined using "Sizing Guidelines for Public Water Supplies", State of Washington, Department of Health (DOH). Fire storage volumes shall be determined using the fire flow and duration as provided in levels of service requirements of Pierce County or municipal ordinance and the purveyor's approved plan (See Pierce County Code Chapter 15.40). Siting of storage facilities should consider locations which provide gravity flow.

G.    General Facility Placement. Below-ground facilities shall be located in accordance with applicable municipal or County ordinance. Where no ordinance applies, water mains shall be installed at a location which is compatible with the existing water system, the terrain, and the location of other utilities.

In addition, all piping, pumping, source, storage, and other facilities shall be located on public rights-of-way or dedicated utility easements. Utility easements must be a minimum of 15 feet in width, and piping shall be installed no closer than 5 feet from the easement's edge. Exceptions to this minimum easement may be approved by the operating water purveyor. Unrestricted access shall be provided to all public water system lines and their appurtenances and public fire hydrants that are maintained by public agencies or purveyors.

H.    Pipe Cover. The depth of trenching, installation of pipes, and backfill shall be such as to give a minimum cover of 36 inches over the top of the pipe. This standard shall apply to transmission, distribution, and service piping. Backfilling up to 12 inches over the top of the pipe shall be evenly and carefully placed. Remaining depth of trench to be filled in accordance with applicable construction standards identified in General Provision. Materials capable of damaging the pipe or its coating shall be removed from the backfill material.

I.    Separation Distances. Whenever possible, transmission and distribution water piping shall be separated at least 10 feet horizontally from on-site waste disposal piping, drainfields, and/or wastewater gravity or force mains. At a minimum, the bottom of the water main shall be 18 inches above the top of the sewer. Closer spacing may be permissible where the sewer piping is constructed to water main standards and has been pressure tested to ensure water tightness prior to backfilling.

(Ord. 96-92S § 1 (part), 1996; Ord. 96-111 §§ 2, 8 (part), 1996; Ord. 94-82S § 3 (part), 1994)

19D.130.060 Standards Review Subcommittee. Amended Ord. 2021-47s

A Standards Review Subcommittee shall be established by the Pierce County Water Utilities Coordinating Committee (WUCC) and shall convene at least annually to review these standards and their implementation. The Subcommittee shall seek input from the Pierce County Fire Marshal and the fire districts in matters related to fire protection standards. Recommendations of the Standards Review Committee shall be submitted to the WUCC and, if revisions are approved, they shall be forwarded to the County Council for consideration, hearings and adoption. (Ord. 96-92S § 1 (part), 1996; Ord. 96-111 §§ 2, 8 (part), 1996; Ord. 94-82S § 3 (part), 1994)

19D.130.070 Severability. Amended Ord. 2021-47s

If any provision of these standards or their application is found to be invalid, the remainder of the standards and their implementations are not affected. (Ord. 96-92S § 1 (part), 1996; Ord. 96-111 §§ 2, 8 (part), 1996; Ord. 94-82S § 3 (part), 1994)