Utah Office of Administrative Rules

R309. Environmental Quality, Drinking Water.

R309-510. Facility Design and Operation: Minimum Sizing Requirements.

R309-510-1. Purpose.

This rule specifies the minimum requirements for the sizing of public drinking water facilities such as sources (and their associated treatment facilities), storage tanks, and pipelines. It is intended to be applied in conjunction with R309-500 through R309-550. Collectively, these rules govern the design, construction, operation and maintenance of public drinking water system facilities. These rules are intended to assure that such facilities are reliably capable of supplying adequate quantities of water which consistently meet applicable drinking water quality requirements and do not pose a threat to general public health.

R309-510-2. Authority.

This rule is promulgated by the Drinking Water Board as authorized by Title 19, Environmental Quality Code, Chapter 4, Safe Drinking Water Act, Subsection 104(1)(a)(ii) of the Utah Code and in accordance with Title 63G, Chapter 3 of the same, known as the Administrative Rulemaking Act.

R309-510-3. Definitions.

Definitions for certain terms used in this rule are given in R309-110 but may be further clarified herein.

R309-510-4. General.

(1) This rule provides minimum quantities and flow rates that shall be used in the design of new systems and in the evaluation of water source, storage facility, and pipeline capacities, unless a public water system has obtained a capacity reduction per R309-510-5. Water demand may vary significantly depending on water system size, type, land use, urbanization, location, precipitation, etc. Therefore, public water systems may submit system-specific water use data to justify alternative sizing requirements in accordance with R309-510-5.

(2) When designing a public water system, the sizing requirements for indoor water use, irrigation, and fire suppression (as required by the local fire code official) shall be included as appropriate.

(3) Local authorities may impose more stringent design requirements on public water systems than the minimum sizing requirements of this rule.

(4) Public water systems shall consider daily, weekly, monthly, seasonal, and yearly variations of source capacity and system demand and shall verify that the capacities of drinking water facilities are sufficiently sized.

(5) The Director may modify the sizing requirements based on the unique nature and use of a water system.

R309-510-5. Reduction of Sizing Requirements.

(1) Water systems that want to use system-specific design criteria that are below the state's minimum sizing requirements may submit a request for a reduction to the Director. Each request shall include supporting information justifying the reduction in source, storage, or pipeline sizing.

(2) Depending on the reduction being sought, the supporting information may include actual water use data representing peak day demand, average day demand for indoor and irrigation uses, fire flow requirements established by the local fire code official, etc. Each reduction request and supporting information will be reviewed on a case-by-case basis because of the wide variety of factors to be considered, such as water system configuration and size, built-in redundancy, water user type, safety factors, method and quality of data collected, water losses, reliability of the source, etc.

(3) Prior to collecting or compiling water use data for a reduction request, a public water system shall consult with the Division of Drinking Water to identify the information needed for a reduction request and to establish a data collection protocol.

(4) The data submitted for a source reduction request shall be sufficient to account for daily, seasonal, and yearly variations in source and demand.

(5) If data justifying a reduction are accepted by the Director, the sizing requirements may be reduced. The requirements shall not be less than the 90th percentile of acceptable readings.

(6) If a reduction is granted on the basis of limited water use, enforceable water use restrictions must be in place, shall be consistently enforced by the water system or local authority, and shall be accepted by the Director.

(7) The Director may re-evaluate any reduction if the nature or use of the water system changes.

R309-510-6. Water Conservation.

Drinking water systems shall use the water resources of the state efficiently. The minimum sizing requirements of this rule are based on typical water consumption patterns in the State of Utah. Where legally-enforceable water conservation measures exist, the sizing requirements in this rule may be reduced on a case-by-case basis by the Director.

R309-510-7. Source Sizing.

(1) Peak Day Demand and Average Yearly Demand.

Sources shall legally and physically meet water demands under two conditions:

(a) The water system's source capacity shall be able to meet the anticipated water demand on the day of highest water consumption, which is the peak day demand.

(b) The water system's source capacity shall also be able to provide one year's supply of water, which is the average yearly demand.

(2) Indoor Water Use.

Tables 510-1 and 510-2 shall be used as the minimum sizing requirements for peak day demand and average yearly demand for indoor water use unless a public water system has obtained a reduction per R309-510-5.

TABLE 510-1

Source Demand for Indoor Use

Peak Average

Type of Connection Day Demand Yearly Demand

Year-round use

Residential 800 gpd/conn 146,000 gal./conn

Equivalent

Residential

Connection (ERC) 800 gpd/ERC 146,000 gal./ERC

Seasonal/Non-residential

use

Modern Recreation Camp 60 gpd/person (See Note 1)

Semi-Developed Camp

a. with pit privies 5 gpd/person (See Note 1)

b. with flush toilets 20 gpd/person (See Note 1)

Hotel, Motel, and Resort 150 gpd/unit (See Note 1)

Labor Camp 50 gpd/person (See Note 1)

Recreational Vehicle

Park 100 gpd/pad (See Note 1)

Roadway Rest Stop 7 gpd/vehicle (See Note 1)

Recreational Home

Development

(i.e., developments

with limited

water use)

(See Note 2) 400 gpd/conn (See Note 1)

NOTES FOR TABLE 510-1:

Note 1. Average yearly demand shall be calculated by

multiplying the number of days in the designated water system

operating period by the peak day demand unless a reduction has

been granted in accordance with R309-510-5.

Note 2. To be considered a Recreational Home Development

(i.e., developments with limited water use) as listed in Table

510-1, dwellings shall not have more than 8 plumbing fixture

units,in accordance with the state-adopted plumbing code, and

shall not be larger than 1,000 square feet. For a new

not-yet-constructed development to be considered as a

development with limited water use, it must have enforceable

restrictions in place that are enforced by the water system or

local authority and are accepted by the Director.

TABLE 510-2

Source Demand for Indoor Use -

Individual Establishments (Note 1)

Type of Establishment Peak Day Demand

(gpd)

(Notes 2 and 3)

Airports

a. per passenger 3

b. per employee 15

Boarding Houses

a. for each resident boarder and employee 50

b. for each nonresident boarders 10

Bowling Alleys, per alley

a. with snack bar 100

b. with no snack bar 85

Churches, per person 5

Country Clubs

a. per resident member 100

b. per nonresident member present 25

c. per employee 15

Dentist's Office

a. per chair 200

b. per staff member 35

Doctor's Office

a. per patient 10

b. per staff member 35

Fairgrounds, per person 1

Fire Stations, per person

a. with full-time employees and food prep. 70

b. with no full-time employees and no food prep. 5

Gyms

a. per participant 25

b. per spectator 4

Hairdresser

a. per chair 50

b. per operator 35

Hospitals, per bed space 250

Industrial Buildings, per 8 hour shift,

per employee (exclusive of industrial waste)

a. with showers 35

b. with no showers 15

Launderette, per washer 580

Movie Theaters

a. auditorium, per seat 5

b. drive-in, per car space 10

Nursing Homes, per bed space 280

Office Buildings and Business Establishments,

per shift, per employee (sanitary wastes only)

a. with cafeteria 25

b. with no cafeteria 15

Picnic Parks, per person (toilet wastes only) 5

Restaurants

a. ordinary restaurants (not 24 hour service) 35 per seat

b. 24 hour service 50 per seat

c. single service customer utensils only 2 per

customer

d. or, per customer served

(includes toilet and kitchen wastes) 10

Rooming House, per person 40

Schools, per person

a. boarding 75

b. day, without cafeteria, gym or showers 15

c. day, with cafeteria, but no gym or showers 20

d. day, with cafeteria, gym and showers 25

Service Stations

a. per vehicle served, or 10

b. per gas pump 250

Skating Rink, Dance Halls, etc., per person

a. no kitchen wastes 10

b. Additional for kitchen wastes 3

Ski Areas, per person (no kitchen wastes) 10

Stores

a. per public toilet room 500

b. per employee 11

Swimming Pools and Bathhouses, per person 10

(Note 4)

Taverns, Bars, Cocktail Lounges, per seat 20

Visitor Centers, per visitor 5

NOTES FOR TABLE 510-2:

Note 1. When more than one use will occur, the multiple

uses shall be considered in determining total demand. Small

industrial plants maintaining a cafeteria or showers and club

houses or motels maintaining swimming pools or laundries are

typical examples of multiple uses. Uses other than those listed

above shall be considered in relation to established demands

from known or similar installations.

Note 2. Source capacity must at least equal the peak day

demand of the system. Determine this by assuming the facility

is used to its maximum, e.g., the physical capacity of the

facility.

Note 3. To determine the average day demand for

establishments listed in Table 510-2, divide the peak day

demand by 2, unless alternative data are accepted by the

Director.

Note 4. Or Peak Day Demand = 20 x (Water Area (ft2)/30) +

Deck Area (ft2)

(3) Irrigation Use.

If a water system provides water for irrigation, Table 510-3 shall be used to determine the peak day demand and average yearly demand for irrigation water use. The following procedure shall be used:

(a) Determine the location of the water system on the map entitled Irrigated Crop Consumptive Use Zones and Normal Annual Effective Precipitation, Utah as prepared by the Soil Conservation Service (available from the Division). Find the numbered zone, one through six, in which the water system is located (if located in an area described "non-arable" find nearest numbered zone).

(b) Determine the net number of acres which may be irrigated.

(c) Refer to Table 510-3, which assumes direct application of water to vegetation, to determine peak day demand and average yearly demand for irrigation use.

(d) Consider water losses due to factors such as evaporation, irrigation delivery method, overwatering, pipe leaks, etc. Apply a safety factor to the irrigation demand in the design accordingly.

TABLE 510-3

Source Demand for Irrigation

Map Zone Peak Day Demand Average Yearly Demand

(gpm/irrigated acre) (AF/irrigated acre)

(Note 1)

1 2.26 1.17

2 2.80 1.23

3 3.39 1.66

4 3.96 1.87

5 4.52 2.69

6 4.90 3.26

NOTE FOR TABLE 510-3:

Note 1. The average yearly demand for irrigation water

use (in acre-feet per irrigated acre) is based on 213 days of

irrigation, e.g., April 1 to October 31.

(4) Variations in Source Yield.

(a) Water systems shall consider that flow from sources may vary seasonally and yearly. Where flow varies, the number of service connections supported by a source shall be based on the minimum seasonal flow rate compared to the corresponding seasonal demand.

(b) Where source capacity is limited by the capacity of treatment facilities, the maximum number of service connections shall be determined using the treatment plant design capacity instead of the source capacity.

R309-510-8. Storage Sizing.

(1) General.

Each public water system, or storage facility serving connections within a specific area, shall provide:

(a) equalization storage volume, to satisfy average day demands for water for indoor use and irrigation use,

(b) fire flow storage volume, if the water system is equipped with fire hydrants intended to provide fire suppression water or as required by the local fire code official, and

(2) Equalization Storage.

(a) All public drinking water systems shall provide equalization storage. The amount of equalization storage varies with the nature of the water system, the extent of irrigation use, and the location and configuration of the water system.

(b) Table 510-4 lists required equalization storage for indoor use. Storage requirements for non-community systems not listed in this table shall be determined by calculating the average day demands from the information given in Table 510-2.

TABLE 510-4

Storage Volume for Indoor Use

Type Volume Required

(gallons)

Community Systems

Residential;

per single resident service connection 400

Non-Residential;

per Equivalent Residential Connection (ERC) 400

Non-Community Systems

Modern Recreation Camp; per person 30

Semi-Developed Camp; per person

a. with Pit Privies 2.5

b. with Flush Toilets 10

Hotel, Motel and Resort; per unit 75

Labor Camp; per unit 25

Recreational Vehicle Park; per pad 50

Roadway Rest Stop; per vehicle 3.5

Recreational Home Development (i.e.,

developments with limited water use);

per connection (See Note 2 in Table 510-1) 400

(c) Where a drinking water system provides water for irrigation use, Table 510-5 shall be used to determine the minimum equalization storage volumes for irrigation. The procedure for determining the map zone and irrigated acreage for using Table 510-5 is outlined in R309-510-7(3).

TABLE 510-5

Storage Volume for Irrigation Use

Map Zone Volume Required

(gallons/irrigated acre)

1 1,782

2 1,873

3 2,528

4 2,848

5 4,081

6 4,964

(3) Fire Flow Storage.

(a) Fire flow storage shall be provided if fire flow is required by the local fire code official or if fire hydrants intended for fire flow are installed.

(b) Water systems shall consult with the local fire code official regarding needed fire flows in the area under consideration. The fire flow information shall be provided to the Division during the plan review process.

(c) When direction from the local fire code official is not available, the water system shall use Appendix B of the International Fire Code, 2015 edition, for guidance. Unless otherwise approved by the local fire code official, the fire flow and fire flow duration shall not be less than 1,000 gallons per minute for 60 minutes.

(4) Emergency Storage.

Emergency storage shall be considered during the design process. The amount of emergency storage shall be based upon an assessment of risk and the desired degree of system dependability. The Director may require emergency storage when it is warranted to protect public health and welfare.

R309-510-9. Distribution System Sizing.

(1) General Requirements.

The distribution system shall be designed to ensure adequate flow and that minimum water pressures as required in R309-105-9 exist at all points within the distribution system.

(2) Peak Instantaneous Demand for Indoor Water Use.

(a) Large or complex water systems may determine peak instantaneous demand using hydraulic modeling. The hydraulic model must either apply an instantaneous peaking factor to account for peak instantaneous demand or use actual peak instantaneous water flow data.

(b) Alternatively, the peak instantaneous demand for a single pipeline shall be calculated for indoor use using the following equation:

Q = 10.8 x N0.64

where N equals the total number of ERC's, and Q equals the total flow (gpm) delivered to the total connections served by that pipeline.

TABLE 510-6

Peak Instantaneous Demand for Indoor Water Use for

Recreational Vehicle Parks

Number of Connections Formula

0 to 59 Q = 4N

60 to 239 Q = 80 + 20N0.5

240 or greater Q = 1.6N

NOTES FOR TABLE 510-6:

Q is total peak instantaneous demand (gpm). N is the

maximum number of connections. However, if the only water use

is via service buildings, the peak instantaneous demand shall

be calculated for the number of plumbing fixture units as

presented in the state-adopted plumbing code.

(d) For small non-community water systems, the peak instantaneous demand for indoor water use shall be calculated on a per-building basis for the number of plumbing fixture units as presented in the state-adopted plumbing code.

(3) Peak Instantaneous Demand for Irrigation Use.

Peak instantaneous demand for irrigation use is given in Table 510-7. The procedure for determining the map zone and irrigated acreage for using Table 510-7 is outlined in R309-510-7(3).

TABLE 510-7

Peak Instantaneous Demand for Irrigation Use

Map Zone Peak Instantaneous Demand

(gpm/irrigated acre)

1 4.52

2 5.60

3 6.78

4 7.92

5 9.04

6 9.80

(4) Fire Flow.

(a) Distribution systems shall be designed to deliver needed fire flow if fire flow is required by the local fire code official or if fire hydrants intended for fire flow are provided. The distribution system shall be sized to provide minimum pressures as required by R309-105-9 to all points in the distribution system when needed fire flows are imposed during peak day demand in the distribution system.

(b) The water system shall consult with the local fire code official regarding needed fire flow in the area under consideration. The fire flow information shall be provided to the Division during the plan review process.

(c) If direction from the local fire code official is not available, the water system shall use Appendix B of the International Fire Code, 2015 edition, for guidance. Unless otherwise approved by the local fire code official, the fire flow and fire flow duration shall not be less than 1,000 gallons per minute for 60 minutes.

KEY: drinking water, minimum sizing, water conservation

Date of Last Change: July 15, 2015

Notice of Continuation: February 10, 2025

Authorizing, and Implemented or Interpreted Law: 19-4-104

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Rule 510: Facility Design and Operation: Minimum Sizing Requirements