* For statutory provisions regulating water quality control, see Water Code § 13000 et seq.

In applying the minimum requirements found in this chapter for design and construction of a water system, consideration shall be given to the quantity of water pumped and stored, the adequacy and dependability of all waterworks facilities, the physical conditions known to exist at the time and place of installation, and the probable operating requirements. (Ord. 383 § 125, 1974).

As used in this chapter the letters “psi” mean pressure in pounds per square inch gauge. (Ord. 383 § 126, 1974).

All facilities shall be of adequate size and capacity and shall be correlated with source facilities and storage facilities to meet the requirements of Section 13.12.040. All facilities shall be designed structurally to withstand the physical stresses to which they shall be subjected and shall be free from structural and sanitary hazards. (Ord. 383 § 127, 1974).

A. The total required water flow for any given service area under consideration or unit water system, except for small water systems, shall be the sum of the minimum fire flow plus the maximum daily domestic water flow requirements. The maximum daily water flow requirements shall be either two, two and one-half, or three and one-half times the average daily water flow requirements depending upon whether the water system is to be metered, unmetered without yard irrigation, or unmetered with yard irrigation.
O_T equals O_F plus 2 O_D for metered service;
O_T equals O_F plus 2.5 O_D for unmetered without yard irrigation;
O_T equals O_F plus 3.5 O_D for unmetered with yard irrigation.
Where: O_T equals the total required water flow, O_F equals the minimum required fire water flow (see Section 13.12.070), and O_D equals the average daily required water flow (see Section 13.12.050). All flows are to be expressed in gallons per minute.
B. Small Water Systems.
1. For small water systems serving four or less residential units, the minimum required water flow shall be two and two-tenths gallons per minute for each unit, if the well has been pump tested according to county standards. A well driller’s yield test may be accepted, but the total required water flow shall be three and three-tenths gallons per minute for each unit for the required flow.
2. The distribution system shall be capable of delivering the required domestic flow for a minimum duration of two hours. A storage tank shall be provided to augment a well supply to furnish the required water flow.
3. The system shall have a hydropneumatic tank to provide a minimum pressure of twenty-five psi in the water system, if necessary. The pressure tank shall have a minimum capacity of two hundred gallons.
4. A variance may be granted by the board of supervisors, after notice and hearing, to the provisions of this subsection pertaining to small water systems. The order granting such variance shall set forth the reasons for the granting of such variance. (Ord. 383B, 1978: Ord. 383 § 140, 1974).

The average required daily water flow in gallons per minute for domestic or developed area used in the water system shall be obtained by the following formula: O_D equals two and one-half times SU times DF, in gallons per minute; where O_D equals the average daily required water flow for domestic use, SU equals the number of service units which reflect type and number of water services, and DF equals the density factor. The average daily required flow in gallon per minute in the water system for commercial, industrial, irrigation and other uses shall be described in detail and supported with data.
Supporting data shall be submitted with all water system improvement plans and shall be subject to the review and approval of the county engineer.

The county engineer shall be guided by, but may adjust the quantities set forth in the following subsections of local condition:
Service Units (SU).
1. Residential: Each single-family dwelling or lot will be counted at the rate of 0.35 service units per capita with a minimum of three capita per lot. Each family dwelling unit of duplex or triplex status, or a mobilehome, shall be counted at the rate of 0.6 service units per family unit. Each family dwelling unit of an apartment building shall be counted at the rate of 0.5 service units per family unit.
2. Commercial, Industrial, Agricultural: Service units are to be based upon actual conditions. Each acre will be counted as a minimum of five service units.
B. Density Factor (DF).
The density factor takes into account the number of service connections involved within any system or section thereof and reflects density and probability. The following density factors are established by this article:
DF equals 2.00 for systems with 5 service connections or less
DF equals 1.60 for systems with 20 service connections
DF equals 0.90 for systems with 40 service connections
DF equals 0.70 for systems with 80 service connections
DF equals 0.60 for systems with 100 service connections
DF equals 0.45 for systems with 200 service connections
Values for DF between the numbers of service connections listed shall be determined by interpolation. (Ord. 383 § 141, 1974).

The distribution system shall be capable of delivering the average daily required domestic water flow for a minimum duration of two hours. (Ord. 383 § 142, 1974).

The water system for all structures shall meet the requirements set forth in Appendix III-A of the California Fire Code. Those areas not served by a public water system shall comply with Section 1142 of the National Fire Codes of the National Fire Protection Association (NFPA 1142). The following types of structures shall be exempt from the above requirements:
A. Buildings within an agricultural zoning district in which at least fifty percent of the total floor space, whether enclosed by walls or not, is used for the storage of farm equipment and supplies;
B. One- and two-family dwellings, if and only if those structures are located within five miles’ driving distance from a water tender or maintain an insurance services office rating (ISO) of “Rural 8” or better. Any one- or two-family dwelling located more than five miles’ driving distance from a water tender or not maintaining an ISO of Rural 8 or better shall store a minimum of two thousand five hundred gallons of water onsite at all times. (Ord. 598 § 2, 2004: Ord. 542 § 2, 1991: Ord. 383A § 1, 1978: Ord. 383 § 143, 1974).

In lieu of the fire flow requirements of Section 13.12.070 the county engineer may approve a fire plan for industrial developments utilizing other fire suppression methods. Such plans may use automatic chemical suppression systems in combination with a reduced fire flow from the water system. (Ord. 383 § 144, 1974).

The distribution system shall be of adequate size and so designed in conjunction with related facilities to maintain normal operating pressures of not less than thirty psi nor more than one hundred psi at the service connection, except that during the periods of maximum hourly demand the pressures shall not be less than twenty-five psi nor more than one hundred and twenty-five psi. The computations for fire flow shall be based upon a minimum of twenty psi residual operating pressure at the hydrant. Water pressures may be greater than one hundred and twenty-five psi if the operator notifies the customer in writing. (Ord. 383 § 160, 1974).

Storage capacity shall be provided in new subdivisions to protect the users from failure of domestic supply and to assure an adequate quantity of water for fire protection in the event of a power or source failure or major disruption of the distribution system. Storage shall be an elevated tank or reservoir such as to provide gravity flow to the point of demand or, an additional power supply or standby power may be used as an alternate. A maintenance plan for standby power systems shall be submitted to the county engineer for approval. Underground storage and storage in pipelines will not be taken into consideration in meeting minimum storage requirements. Storage shall be determined by the following criteria:

(Ord. 383 § 161, 1974).

The engineer for the developer shall file with the county engineer a computation of the water supply requirements for a subdivision or development to be served by a water utility. (Ord. 383 § 162, 1974).

Water as drawn from wells and springs and treated water sources, shall meet the U.S. Public Health Service “Drinking Water Standards” as to bacteriological quality. Water from untreated surface sources shall meet water quality standards as established by the county health department. (Ord. 383 § 170, 1974).

The chemical constituents should not occur in excess of the concentrations recommended by the U.S. Public Health Service standards where other more suitable supplies are available in the judgment of the county health department. In addition to the above chemical standards, the taste, odor and appearance of the water should be such that it is generally acceptable to the consumers. (Ord. 383 § 171, 1974).