248 CMR, § 10.14

Current through Register 1537, December 20, 2024

Section 10.14 - Water Supply and the Distribution System

(1)General. All water for human consumption shall comply with the requirements of the Safe Water Drinking Act (SWDA), 42 U.S.C. § 300fet. seq.

(a) NFPA 13D multipurpose residential fire sprinkler systems which utilize potable cold- water piping as part of a fire sprinkler protection system in one-and two-family dwellings shall comply with the requirements of 248 CMR 10.14. Installation of these systems includes the direct connection of sprinkler heads to potable water piping. When installing said system, the plumber shall adhere to the design plans of a Massachusetts professional engineer, who is responsible for ensuring the design complies with 248 CMR and NFPA 13D (2022 edition), including the requirements as to pipe sizing and dimensions to ensure the proper functioning of the system as well as the safety of the consumers who will rely on that system.

(b)Potable Water Supply.

1.Buildings.

a. Every building used for human occupancy or habitation shall be provided with an adequate supply of potable water.

b. Every building used for human occupancy or habitation shall be provided with an adequate supply of hot water.

2.Use of Non-potable Water Prohibited. Only potable water shall be accessible to plumbing fixtures supplying water for:

a. drinking;

b. bathing;

c. culinary use; or

d. the processing of food, medical or pharmaceutical products.

(c)Building Water Piping. The building water piping shall be of sufficient size to furnish water to the building in the quantities required elsewhere in 248 CMR 10.00.

(2)Designing and Sizing the Building Water Distribution System.

(a)Methods to Be Used.

1. The cold-water supply from the meter or main control valve when no meter is present to all branches, risers, final connection to fixtures and other connections shall be based on the total demand and procedures outlined within 248 CMR 10.14.

2. The minimum size of a fixture supply pipe shall be in accordance with 248 CMR 10.14(4): Table 1.

3. Sizing the building water main, branch distribution, risers and fixture supply piping shall be determined using 248 CMR 10.14(4): Tables 1, 2, and 3. Exception: A system designed by a Massachusetts professional engineer.

4. A demand factor, as recognized in 248 CMR 10.14(4): Table 2 shall be applied to determine the minimum diameter pipe size for the building main and water distribution system piping.

5. The minimum size of a fixture water supply pipe shall be in compliance with 248 CMR 10.14(4): Table 1: Minimum Sizes of Individual Fixture Branches and Factor Values.

6. The individual fixture branch shall be extended to the fixture connector and terminate with a fixture shut off valve.

7. Fixture connectors shall not exceed 30 inches and shall be product accepted by the Board.

Exception: Dishwashers, washing machines and icemakers.

Table 1

Minimum Sizes of Individual Fixture Branches and Factor Values

Type of Fixture or Device	Nominal Pipe Size (Inches)	Factor Value
Bathtub (with or without single shower head)	1/2	2
Bidet	3/8	1
Drinking Water Station	3/8	1
Dishwasher (Domestic)	1/2	2
Dishwasher (Commercial)	3/4	6
Kitchen sink, Residential	1/2	2
Kitchen sink, Commercial (Pot and Scullery)	3/4	6
Vegetable Prep or Bar Sink (Residential)	1/2	2
Hand Wash Sinks	3/8	1
Shampoo Sinks	3/8	1
Lavatory	3/8	1
Utility Laundry Sinks 1, 2, or 3 compartments	1/2	2
Shower Valve (single head)	1/2	2
Shower Valve (Multiple heads)	3/4	6
Sinks (service, slop)	1/2	2
Sinks flushing rim	3/4	6
Laundry Valve	1/2	2
Urinal (flushometer type)	3/4	6
Toilet (tank type)	3/8	1
Toilet (flush valve type)	1	12
Hose Connections/Sillcocks/Wall Hydrants	1/2	2

Table 2

Occupancy Use	Demand Factors
Residential
One or Two Family Dwelling	0.50
Multi-residential	0.35
Hotel	0.70
School
General	0.75
Shower Room	1.00
Institutional
General	0.45
Assembly
General	0.25
Restaurant, Cafe	0.70
Club House	0.60
Business and Mercantile
General
Industrial	0.25
Laundry	1.00
INDUSTRIAL
General, Exclusive of Process Piping	0.90

Table 3

Capacity Values for Service, Mains, Risers and/or Branches

Nominal Pipe or Tubing Sizes (inches)	Capacity Value
1/2	1 to 4
3/4	4.1 to 9
1	9.1 to 16.5
11/4	16.6 to 28
11/2	28.1 to 55
2	55.1 to 107.5
21/2	107.6 to 182.5
3	182.6 to 287.5
31/2	287.6 to 425
4	425.1 to 700
5	700.1 to 1100
6	1100.1 to 1300

8.Example: 248 CMR 10.14(4): Tables 1, 2 and 3 are used to determine the size of the cold water main for a one family residence having the following fixtures:

A	Two	Toilets (Tank type)
B	Two	Lavatories
C	One	Bathtub
D	One	Shower Stall
E	One	Utility Sink or Laundry Valve
F	One	Dishwasher (Domestic)
G	One	Kitchen Sink
H	Two	Wall Hydrants

Factor Values (248 CMR 10.14: from Table 1)

Hot	Cold
A	Two	Toilets (tank type) X 1	2
B	Two	Lavatories X 1	2	2
C	One	Bathtub	2	2
D	One	Shower Stall	2	2
E	One	Utility Sink or Laundry Valve	2	2
F	One	Dishwasher (Domestic)	2
G	One	Kitchen Sink	2	2
H	Two	Wall Hydrant	4
		Total	12	16	28

a.248 CMR 10.14(4): Table 2 indicates a Demand Factor of 0.50 for a Single or Two family dwelling.

b. Multiplying the total Factor Value of 28 by the Demand Factor of 0.50 results in a Capacity Value of 14.0

c. A Capacity Value of 14 is between 9.1 and 16.5 in 248 CMR 10.14(4): Table 3 and the related pipe size is equals to a one-inch diameter pipe.

(b)Prevent Water Hammer.

1.Installation and Design Requirements.

a. All building water supply systems in which quick acting valves and solenoid valves are installed shall be provided with devices to absorb high pressures resulting from the quick closing of these valves.

b. These pressure-absorbing devices shall be air chambers that are provided with a means for restoring the air to the device should the chambers become waterlogged, or other Product-accepted mechanical devices.

c. Water pressure absorbers shall be placed as close as possible to the quick acting valves and shall be accessible for maintenance or replacement. See248 CMR 1.14: Example 2.

2.Pressure Absorbing Devices. A mechanical pressure absorbing device may be installed:

a. at the ends of long pipe runs of pipe; or

b. connected to piping serving batteries of fixtures.

3.Mechanical Devices. Where mechanical devices are used, the manufacturer's specifications shall be followed as to location and method of installation.

10.14: Example 2 - Pressure Absorbing Device

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(c)Minimum Pressures Required in Water Distribution System. When sizing a water distribution piping system, the minimum flow pressure at the point of discharge for each fixture shall not be less than that shown in 248 CMR 10.14(4): Table 4: Minimum Flow Pressure and Maximum Flow Rates. Exception: On-demand domestic water heaters.

Table 4

Minimum Flow Pressure and Maximum Flow Rates

Fixture or Device	Flow Pressure PSI	Flow Rate G.P.M.
Lavatory Faucet (Residential)	8	1.5
Lavatory Faucet (Non-residential)	8	.5
Kitchen or Bar Faucet (Residential)	8	2.2
Sink Faucet (Non-residential)	8	4.5
Bathtub Faucet	8	6
Laundry Valve or Faucet (Residential)	8	5
Shower Head	8	2*
Tank-Type Toilet	8	1.28
Flushometer-Type Toilet	15-20	1.28
Flushometer-Type Urinal	15	.5
Drinking Water Station	0.75
Outside Faucet or Hydrant	10	5

* Exception: Emergency showers as defined in 248 CMR 10.10 (12)

(d)Inadequate Water Pressure. Whenever water pressure from the street main, service, or other source of supply is insufficient to provide flow pressures at fixture outlets as required under 248 CMR 10.14(2)(c), a booster pump and pressure tank or other means in compliance with 248 CMR 10.00 shall be installed on the building water supply system.

1.Water Pressure Booster Systems. When water pressure in the public water main or individual water supply system is insufficient to supply the probable peak demand flow to all plumbing fixtures, a water pressure booster system shall be installed:

a. In one, two and three-family dwellings, a properly sized booster pump shall be installed.

b. In other than one, two and three-family dwellings, a booster system shall be designed by a Massachusetts professional engineer.

(e)Excessive Water Pressure. If the pressure at any plumbing fixture, device or appurtenance exceeds 80 PSIG, a pressure reducing valve shall be installed on the water piping upstream of the device, or appurtenance to limiting the pressure to 80 PSIG. Where pressure reducing valves are installed, a pressure gauge with a minimum range of 0-150 PSIG shall be installed within 24 inches downstream of the pressure reducing valve. See 10.14: Example 3. Exception: Water service supply piping upstream and downstream of a water pressure booster.

10.14: Example 3 - Pressure Reducing Valve

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(f)Return Circulation - Where Required. Hot water supply systems in buildings where the developed length of hot water piping from the source of the hot water supply to the farthest fixture supply exceeds 75 feet shall be of the total return circulation type. For purposes of 248 CMR 10.14, the "source" shall be the water heater or the recirculation loop. The minimum size recirculating line shall be 1/2 inch.

(3)Installation of the Building Water Distribution System.

(a) All valves shall be accessible.

(b)Main Control Valve.

1. A full-port main control valve shall be installed in the water supply main on the discharge side of each water meter or on the incoming water service where no meter is present.

2. The valve shall be not less than the size of the building water service pipe. See 10.14: Example 4.

3. A draw off valve shall be installed upstream of main control valve on the discharge side of each water meter. See 10.14: Example 4.

10.14: Example 4 - Main Control Valve

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(c)Branch and Riser Valves.

1. A full-port valve shall be installed at the base of each water supply riser when servicing multiple fixtures on levels above the first floor. A draw off valve shall be installed upstream of each riser valve. See 10.14: Example 5.

2. Branch valves installed servicing multiple fixtures shall be full port.

3. In multistory buildings, a full-port valve shall be installed at the top of each water supply that is an upstream supply pipe from a booster system.

4. Dead Ends shall not be allowed. (see definition).

10.14: Example 5 - Risers

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(d)Valves in Multiple Dwelling Units. One or more main control valve shall be provided so that the water to any unit may be shut off without stopping the flow of water to other units. These valves shall be accessible to the unit supplied without requiring access to other units. (e) All main control valves, branch/riser valves and other devices installed on mains and branches of the water supply system shall be of the full-port type.

(f)Individual Fixture Valves.

1. In all buildings, water supply pipes feeding plumbing fixtures, devices, or appurtenances shall be provided with a valve to shut off the water to that fixture, device, or appurtenance. Exception: Residential shower valves, tub and shower valves, tub fillers and other similar type fixtures.

2. All outside sillcocks, hose bibbs and wall hydrants shall be separately controlled by a shutoff valve installed inside the building.

(g)Tank Controls. Supply lines from pressure or gravity tanks shall be provided with valves at or near the tanks.

(h)Water Heating Equipment Valve. The cold-water branch to each hot water storage tank or water heater shall be provided with a valve located near the equipment and above the top of the tank. See 10.14: Example 6.

10.14: Example 6 - Valve for Water Heater

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(i)Drain Valves.

1. In other than single family homes, a drain valve shall be installed at all low points of piping so that every portion of the water piping system can be drained.

2. An accessible drain valve shall be required upstream and near the meter or main control valve. See 10.14: Example 4.

(j)Metering Devices with Check Valves. When a metering device with a check valve or backflow preventor is installed creating a closed system, a properly sized thermal expansion tank shall be installed as close as possible to the metering device.

(k)Hose Connections.

1. Outside Hose connections, sillcocks or wall hydrants shall be installed in all residential buildings no more than 100 feet apart.

2. In all commercial buildings, Sillcocks and hose connections shall only be required in:

a. mechanical rooms;

b. mechanical penthouses; or

c. mechanical areas of similar use and nature.

3. A backflow preventer or vacuum breaker shall be installed on all sillcocks, hose connections and wall hydrants including faucets that incorporate a hose thread outlet.

(l)Prohibited Valves and Connections.

1. Saddle valves.

2. No water supply line shall be tapped, burned, welded, or drilled, other than mechanical devices that have been Product-accepted by the Board which are designed and engineered to create penetration in piping for specific joining methods may be used.

(4)Disinfection of Potable Water System Piping. When necessary, the Inspector shall require that a Potable water distribution system, or any part thereof, which has been installed or repaired may require disinfection in accordance with one of the following methods before it is placed in operation:

(a) The system, or part thereof, shall be filled with a water and chlorine solution which contains 50 parts per million of available chlorine; and the same shall then be allowed to stand six hours before the system, or part thereof, is flushed and returned to service.

(b) The system, or part thereof, shall be filled with a solution which contains 100 parts per million of available chlorine, and the same shall then be allowed to stand two hours before the system, or part thereof, is flushed and returned to service.

(c) Where it is not possible to disinfect a potable water storage tank as provided by 248 CMR 10.14(7)(a) or (b), the entire interior of the tank shall be swabbed with a solution which contains 200 parts per million of available chlorine; and the solution shall then be allowed to stand two hours before the tank is flushed and returned to service. For a potable water filter or similar device, the Massachusetts Department of Environmental Protection shall determine the dosage.

(5)Hot Water Supply System.

(a) In all occupied premises and structures, hot water shall be supplied to all plumbing fixtures and equipment used for bathing, washing, culinary purpose, cleansing, laundry, or building maintenance.

(b) Hot water storage systems shall be designed to adequately accommodate the fixtures being served.

(c) The maximum temperature of domestic hot water in residential buildings shall not exceed 130°F. Plumbing fixtures requiring higher temperatures for their proper use and function, such as dishwashers and hot water dispensers shall be exempted from 248 CMR 10.14.

Minimum and Maximum Hot Water Temperatures

Hot Water Temperatures (Fahrenheit)
Minimum	Maximum
Residential	120	130*
Water Entering the Sanitary Drainage System	150
Shower Valve	120	120
Tub Filler	120	120
Public & Employee Lavatory	120	120
Residential Lavatory	120	130
Emergency Showers & Eyewash	60	100
Hand Sink in Commercial Kitchen	120	120
Kitchen Type Sink in Office	120	120
Service Sink & Scullery Sink	120	140
* See 10.14 (5)(c) for Exception

(6)Tank Type Water Heaters and Storage Tanks.

(a)Working Pressure of Storage Tank. To determine the working pressure of a hot water tank as required by M.G.L. c. 142, § 18E, the street or service pressure only shall be considered, unless a water pressure booster system is used to raise the house pressure above the street pressure.

(b)Tank Drains. A storage tank shall be equipped with a drain valve for emptying at the tank lowest point accept when otherwise allowed by the Board.

(c)Cold Water Supply.

1. A check valve shall not be installed in the cold-water supply to any hot water heater or hot water storage tank.

2. A properly sized thermal expansion tank may be installed to prevent excessive pressure from developing due to thermal expansion.

(d)Prohibited Methods of Water Heating.

1.Hot Water Generators. No coils, boosters or other hot water heating devices shall be installed in direct contact with the heat generating source of any building heating system or heating unit.

2.Systems Without Automatic Control. No domestic hot water storage system, connected with or to, a direct heating device or appliance, shall be installed in any basement of any building or other unattended area unless such installation has fully automatic control to prevent raising of the temperature of the water in any part of the storage tank to 212°F.

(e)Large Volume Water Heaters and Storage Tanks.

1. Water heaters and storage tanks shall be stamped as ASME compliant when:

a. Installed in other than a private residence or a single condominium unit where the heater is serving only that unit;

b. Have a storage capacity of over 120 gallons and/or a recovery equal to or greater than 200,000 B.T.U.; and

c. are direct or indirect fired. When determining the B.T.U. rating for an indirect fired water heater, the maximum output of the stored or transferred energy shall be utilized.

Examples: An 80-gallon tank with a recovery rate 210,000 BTU must comply with ASME requirements. Two tanks installed, each with 100-gallon capacity with an indirect water heater with a recovery rate of 199,000 BTU feeding tanks shall meet ASME requirements.

Exception: Water heaters and storage tanks which meet the following requirements:

a. The tank conforms with the following UL-174 testing:

i.Section 33. Two times the maximum working pressure or 300 PSIG maximum;

ii.Section 22. 150 PSIG and 210° maximum.

b. The tank has a minimum of a ten year warranty

c. A maximum of four tanks may be installed in tandem.

2.ASME Data Sheet.

a. Copies of an ASME data sheet attesting to the conformance with the requirements of the applicable section of the Code and signed by an authorized and qualified inspector shall be furnished to the owner and/or installing contractor.

b. A copy of the data shall be permanently displayed in a suitable mounting on a wall adjacent to the water heater.

(f) Safety Devices for Water Heaters Safety devices to be used on hot water tanks, tankless and on-demand heaters shall be installed to comply with the provisions of M.G.L. c. 142, § 19 and Standard ANSI 221.22.

1.Pressure Relief Valves.

a. Pressure relief valves installed on direct-fired water heaters having up to 200,000 BTU per hour input shall have a listed rating of not less than the heater input.

b. Pressure relief valves for on-demand water heaters shall have a listed rating of not less than the water heater input.

c. For tankless heaters connected to low pressure steam and hot water heating boilers, the pressure relief valve shall be sized according to 248 CMR 10.14(6)(f): Table 5, as follows:

Table 5

Heater Rating (GPM)	Valve Size
Up to 5	1/2-inch
Over 5 up to 20 Standard Z21.22 applies	3/4-inch
Over 20 up to 50	1-inch
Over 50 ASME Standard applies	1 - 11/4-inch

2.Combination Temperature and Pressure Relief Valves. (T&P) All storage water heating equipment capable of heating water in excess of 212°F shall be equipped with a properly sized T&P relief valve.

a. T&P relief valves shall meet the requirements of pressure relief valves as provided in 248 CMR 10.14(6)(f)1.

b. A T&P valve shall be installed in a tapping directly in or on the tank, within 12 inches of the top of a vertical tank, or within six inches of the top of a horizontal tank, with no fittings between the valve and the tank, except that a bushing may be used to reduce the tapping to fit the valve, or the valve shall be installed in the hot water outlet pipe as close to the top of the tank as possible but in no case more than five inches from the top of the tank.

c. The discharge outlet if the T&P relief valve shall be full-size and pipe using non-ferrous material or tubing rated to withstand the maximum relief valve temperature with no shut-off, to a fixture or a point to within twelve inches of the floor.

d. Heaters and storage tanks with ratings in excess of 200,000 BTU shall be equipped with T&P relief valves in compliance with the requirements of ASME and the current ANSI Z21.22 Standard.

3.Vacuum Relief Valves.

a. Tank type water heaters and storage tanks shall be protected against loss of water from siphoning due to loss of supply pressure by a vacuum relief valve installed in the cold-water supply line at a level above the top of the heater or tank with no shut off valve installed between the vacuum relief valve and the tank.

b. Vacuum relief valves shall be a minimum of one pipe size smaller than the tank drain size.

c. Vacuum relief valves may be installed in multiples and in compliance with 248 CMR 10.14(6)(f)3. Table 6.

Table 6

Vacuum Valve Sizing Chart
Size of Tank Drain	Number of 1/2" Valves Required	Number of 3/4" Valves Required
1/2"	1
3/4"	1
1"	2	1
13/4"	3	2
11/2"	4	3
2" and Larger	5	4

(g)Combination Potable Water/Space Heating System. These systems shall comply with the following requirements. See 10.14: Example 7.

1. The maximum distance from the water heater to the fan coil and returning to the water heater shall not exceed 100 feet in developed length.

2. All piping materials between the water heater and coil shall be incompliance with 248 CMR 3.04: Product, Design, and Testing Standards and 248 CMR 10.06.

3. Must contain an electronically controlled pump timer which operates at least once every six hours for a minimum of 60 seconds.

4. A properly sized potable water expansion tank shall be installed.

5. A mixing valve for service to the plumbing fixtures shall be installed.

10.14: Example 7

Combination Potable Water/Space Heating System

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(h)Identification Tags for Water Heaters. Metal or foil tags permanently attach to most water heaters are considered in compliance with the provisions of M.G.L. c. 142, § 17.

(7)Protection of Potable Water Supply.

(a)General. A potable water supply system shall be designed, installed, and maintained in such manner as to prevent contamination from non-potable liquids, solids, or gases from being introduced into the potable water supply through cross connections or any other piping connections to the system.

(b)Identification of Potable and Non-potable Water. In all buildings where potable water and non-potable water is installed within the same building or structure, the following additional conditions must be satisfied as well as those conditions required for each individual piping system:

1. The potable and non-potable piping systems shall be labeled or painted in the following manner:

a. at a minimum of every ten feet;

b. at all changes of direction;

c. on each side of a penetration through a partition, wall, ceiling or roof;

d. at every shut off valve;

e. for potable water (color-coded green) and non-potable water (color-coded yellow), the labels shall be;

i. black lettering indicating "safe water" for potable and "unsafe water" for non-potable;

ii. the letters shall be sized equal to a minimum of the pipe diameter. However, for piping with a diameter exceeding two inches, said lettering does not need to be larger than two inches.

f. Non-potable water shall be identified at each outlet location.

(c)Cross Connection Control.

1. Cross connections between potable water systems and other systems or equipment containing water or other substances of unknown or questionable safety are prohibited; except when and where, as approved by the Massachusetts Department of Environmental Protection (DEP) or its designee, suitable protective devices such as the Reduced Pressure Zone Backflow Preventer or equal are installed, tested, and maintained to insure proper operation on a continuing basis.

2. No plumbing permit shall be issued for cross connection installations that require Reduced Pressure Zone Backflow Preventers or Double Check Valve Assemblies until the application for a permit is accompanied by a letter of approval from the Massachusetts (DEP) or its designee.

3. The (DEP) or its designee shall be the authority having jurisdiction for the type of cross connection control required. The (DEP) shall be responsible for preventing the contamination of drinking water to the last free flowing outlets or consumer's tap.

(d)Interconnections.

1.Individual Water Supplies. Cross connections between an individual water supply and a potable public supply shall not be made unless specifically approved by the Massachusetts (DEP).

2.Public Water Supplies. Interconnection between two or more public water supplies shall be permitted only with the approval of the health authority having jurisdiction.

(e)Foreign Materials. No materials or substances that could produce either toxic condition, taste, odor, or discoloration in a potable water system shall be introduced into or used in such systems.

(f)Used Piping. Piping which has been used for any other purpose than conveying potable water shall not be used for conveying potable water.

(g)Self Feeding Water Connections to Heating Boilers.

1. Potable water connections to a heating boiler shall be provided with an approved back flow preventer or air gap in the water line to prevent cross connection.

2. Backflow preventers shall not be required on manually controlled water supply lines to residential type steam and/or gravity fed hot water space heating systems.

(h)Prohibited Connections to Fixtures and Equipment. Connection to the potable water supply system for the following shall be protected against backflow:

1. bidets;

2. operating, dissection, embalming, and mortuary tables or similar equipment -- in such installation, the hose used for water supply shall terminate at least 12 inches away from every point of the table or attachments;

3. pumps for non-potable water, chemicals, or other substances; note that priming connections may be made only through an air gap;

4. building drainage, sewer, or vent system; and

5. any other fixture of similar hazard.

(i)Refrigerating Unit Condensers and Cooling Jackets.

1. Except where potable water provided for a refrigerator condenser or cooling jacket is entirely outside the piping or tank containing a toxic refrigerant, with two separate thicknesses of metal separating the refrigerant from the potable water supply the inlet connection shall be provided with an approved double check valve installation.

2. Also adjacent to and at the outlet side of the check valve, an approved pressure relief valve set to relieve at five PSIG above the maximum water pressure at the point of installation shall be provided if the refrigeration units contain more than 20 pounds of refrigerants.

(j)Chemical Cleaning Dispensers.

1. Devices directly connected to the potable water system. (hard piped)

a. Shall require a plumbing permit.

b. The public water supplier shall determine the proper backflow device to be installed.

2. Devices connected to the hose end of a faucet:

a. Shall not require a plumbing permit;

b. All dispensers shall have an Air Gap or, an alternative Certification of Listing under the ASSE 1055B Standard.

c. A pressure bleeder device shall be provided which will visually free flow water through the atmosphere from the faucet connection to a sink or drain. The bleeder device shall connect to the water source utilizing a quick disconnect coupling.

d. The Device that attaches to the Faucet shall be so arranged, so it is one piece that will not allow theremoval of the bleeder from the Quick disconnect portion of this device.

(k)Water Recycling/Re-use Prohibited.

1. Water used for cooling of equipment or other processes shall be discharged into the drainage system through an air gapped indirect waste. Under conditions where water shortage may occur, the water used for cooling may be used for non-potable purposes. Water used for cooling of equipment or other processes shall not be returned to the potable water system.

2.Exceptions. Water recycling systems may be installed if Special-permission under 248 CMR 3.04(3) has been granted by the Board. Systems include, but limited to:

a. dedicated gray water systems;

b. black water systems;

c. on site wastewater treatments systems;

d. systems Product-accepted by the Board shall not require Special Permission.

(l)Protection Against Backflow and Back siphonage.

1.Water Outlets. A potable water system shall be protected against backflow and back siphonage in accordance with M.G.L. c. 111, § 160A, and 310 CMR: Department of Environmental Protection relative to protection of the potable water supply.

a.Air Gap. An air gap as defined in 248 CMR 10.03 between the potable water outlet and the flood level rim of the fixture it supplies or between the outlet and any other source of contamination.

i. The minimum required air gap shall be measured vertically from the lowest end of a potable water outlet to the flood rim of the fixture or receptacle into which it discharges and shall be twice the effective opening of the potable water outlet.

ii. If the outlet is found to be at a distance that is less than three times the effective opening away from a wall or similar vertical surface; the minimum required air gap shall be three times the effective opening of the outlet.

iii. In no case shall the minimum required air gap be less than shown in 248 CMR 10.14(8): Table 7: Minimum Air Gaps for Plumbing Fixtures:

b.Backflow Preventer. A backflow preventing device or vacuum breaker to prevent the drawing of contamination into potable water system.

Table 7

Minimum Air Gaps for Plumbing Fixtures

Minimum Air Gaps For Plumbing Fixtures	Minimum Air Gap
Minimum Air Gaps For Plumbing Fixtures	When not affected by a near wall	When affected by a near wall
Lavatories and other fixtures with effective openings not greater than one half inch in diameter.	1 inch	1.50 inches
Sink, laundry sinks, goose neck bath faucets and other fixtures with effective openings not greater than three quarters of an inch diameter.	1.5 inches	2.25 inches
Over rim bath fillers and other fixtures with effective openings not greater than one-inch diameter.	2 inches	3 inches
Effective openings greater than one inch	2 times the diameter of the effective opening	2 times the diameter of the effective opening

2.Devices for the Protection of the Potable Water Supply. Approved backflow preventers or vacuum breakers shall be installed on any plumbing fixture or equipment where the potable water supply outlet may be submerged and cannot be protected by a minimum air gap.

a.Labeling.

i. Piping after each device shall be labeled as "Water Subject to Questionable Safety" in accordance with 248 CMR 10.14(8)(b)1.a. through f.

3.Installation of Devices.

a.Vacuum Breakers.

i. Vacuum breakers shall be installed with the critical level at least six inches above the flood level rim of the fixture they serve and on the discharge side of the last control valve to the fixture.

ii. No shut-off valve or faucet shall be installed beyond the vacuum breaker.

iii. For closed equipment or vessels such as pressure sterilizers the top of the vessel shall be treated as the flood level rim but a check valve shall be installed on the discharge side of the vacuum breaker.

b.Reduced Pressure Zone Backflow. A reduced pressure zone type backflow preventer may be installed subject to full static pressure. Where damage may occur to the building or structure due to water discharge from the vent port precautions shall be taken.

c.Devices of All Types.

i. Backflow and back siphonage preventing devices shall be accessibly located preferably in the same room with the fixture they serve.

ii. Installation in utility or service spaces, provided they are readily accessible, is also permitted.

4.Tanks and Vats - Below Rim Supply.

a. Where a potable water outlet terminates below the rim of a tank or vat and the tank or vat has an overflow of diameter not less than given in 248 CMR 10.14(6): Table 8: Sizes of Overflow Pipes for Water Supply Tanks, the overflow pipe shall be provided with an air gap as close to the tank as possible.

b. The potable water outlet to the tank or vat shall terminate a distance not less than 11/2 times the height to which water can rise in the tank above the top of the overflow.

c. This level shall be established at the maximum flow rate of the supply to the tank or vat and with all outlets except the air gap, overflow outlet closed.

d. The distance from the outlet to the-high water level shall be measured from the critical point of the potable water supply outlet.

Table 8

Sizes of Overflow Pipes for Water Supply Tanks

Maximum Capacity of Water Supply Line to Tank	Diameter of Overflow Pipe (inches ID)
0 - 50 G.P.M.	2
51 - 100 G.P.M.	21/2
101 - 165 G.P.M.	3
166 - 355 G.P.M.	4
356 - 640 G.P.M.	5
641 - 1,040 G.P.M.	6
OVER 1,040 G.P.M.	8

5.Connections Not Subject to Back Pressure.

a. Where a water connection is not subject to back pressure, a non-pressure type vacuum breaker shall be installed on the discharge side of the last valve on the line serving the fixture or equipment.

b. A list of some conditions requiring protective devices of this kind is given in in 10.14 Table 9: Cross Connections Where Protective Devices Are Required and Critical Level (C-L) Settings for Backflow Preventers.

Table 9

Sizes of Drain Pines for Water Tanks

TANK CAPACITY (Gallons)	DRAINPIPE SIZE (Inches)
Up to 750	1"
751 - 1,500	11/2"
1,501 - 3,000	2"
3,001 - 5,000	21/2"
5,001 - 7,500	3"
7,500 and Larger	4"

6.Barometric Loop. Water connections not subject to back pressure where an actual or potential backflow or back siphonage hazard exists may in lieu of devices specified in 248 CMR 10.14(8)(k)2., be provided with a 35-foot barometric loop. Barometric loops shall precede the point of connection.

7.Pressure Type Vacuum Breakers. Water connections not subject to backpressure where an actual or potential backflow or back siphonage hazard exists may be protected by the installation of a pressure type vacuum breaker, provided that such device is installed with the critical level a minimum of 12 inches above the highest outlet or fixture served by the connection.

8.Anti-siphon or Backpressure Valves.

a. An anti-siphon or backpressure valve shall be installed on any chemical metering pump that pumps any chemical into a potable water supply to prevent back siphonage.

b. The anti-siphon or back-pressure valve must be spring loaded and set at a minimum of five PSIG (An example may be an anti-siphon or back-pressure valve installed on a positive displacement metering pump's discharge line and pumping sodium hypochlorite into a water main at a well house for disinfection purposed.)

Table 10

Cross Connections Where Protective Devices Are Required and Critical Level (C-l) Settings for Backflow Preventers

Fixture or Equipment	Method of Installation
Aspirators and ejectors	C-L at least six inches above flood level or receptacle.
Dental units	On models without built-in vacuum breakers -- C-L at least six inches above flood level rim of bowl.
Dishwashing machines	C-L at least six inches above flood level of machine. Install on both hot and cold water supply lines.
Flushometers (closet and urinal)	C-L at least six inches above top of fixture supplied
Garbage can cleaning machine	C-L at least six inches above flood level of machine. Install on both hot and cold water supply lines.
Hose outlets	C-L at least six inches above highest point on hose line.
Laundry machines	C-L at least six inches above flood level of machine. Install on both hot and cold water supply lines.
Lawn sprinklers	C-L at least 12 inches above highest sprinkler or discharge outlet.
Steam tables	C-L at least six inches above flood level.
Tank and vats	C-L at least six inches above flood level rim or line.
Trough urinals	C-L at least six inches above perforated flush pipe.
Flush tanks	Must be equipped with approved ball cock. Where ball cocks contact tank water they must be equipped with a vacuum breaker at least one inch above the overflow outlets. Where a ball cock does not contact tank water install the ball cock outlet at least one inch above the overflow outlet or provide a vacuum breaker as specified above.

Table 11

Acceptable Types of Backflow Preventers for Prevention of Cross Connections on Potable Water

AG = Air Gap RPBP = Reduced Pressure Backflow Preventer DCVA = Double Check Valve Assembly AVB = Atmospheric Vacuum Breaker PVB = Pressure Vacuum Breaker BPIAV = Backflow Preventer w/Intermediate Atmospheric Vent
Type of Hazard on Premises	Acceptable Types of Backflow Preventors					Comments*
AG	RPBP	DCVA	AVB	PVB BFPAV
1. Sewage Treatment Plant	X	X
2. Sewage Pumping Station	X	X
3. Food Processing	X	X	X*	*If no health hazard exists
4. Laboratories	X	X	X*	*If no health hazard exists
5. Fixtures with hose threads on inlets	X	X	X	X	In addition to an air-gap separation, all fixtures that have threaded hose type connections shall at a minimum, be equipped with an AVB
6. Hospitals, Mortuaries & Clinics	X	X
7. Plating Facilities	X	X
8. Irrigation Systems**	X	X	X*	X**	Each case should be evaluated individually. An AVB may be used if no back pressure is possible and no health hazard exists. * A PVB should be installed if back pressure is possible.
9. Systems or Equipment Using Radioactive Material	X	X
10. Submerged Inlets	X	X	X*	*If no health hazard exists and no back-pressure is possible
11. Dockside Facilities	X	X
12. Valves Outlets or Fixtures with Hose Attachments		X	X	X*	Each case should be evaluated
12. Valves Outlets or Fixtures with Hose Attachments		individually *If no health hazard exists and no back-pressure is possible
13. Commercial Laundries & Dry Cleaners	X	X
14. Commercial Dishwashing Machines	X	X	X*	*If no health hazard exists
15. High- and Low-Pressure Boilers	X	X*	*If chemicals are added
16. Low Pressure Heating Boilers	X	Residential and small commercial having no chemicals added
17. Photo Processing Equipment	X	X
18. Reservoirs - Cooling Tower Recirculating Systems	X	X
19. Fire Protection Systems: For cross connection control, fire protection systems may be classified on the basis of water source and arrangement of supplies as follows: (a) Class 1: Direct connection from public water system mains only; no pumps, tanks, or reservoirs; no physical connection from other water supplies; no antifreeze or other additives of any kind; all sprinkler drains discharge to atmosphere, dry wells, or other safe outlets. These systems may or may not have fire department connections. Refer to 310 CMR 22.22(9)(d)1.	X	X	X	A backflow prevention assembly does not have to be installed on existing fire protection systems installed prior to March 21, 1997, provided that the fire protection system is registered with the public water system, equipped with a UL listed alarm check valve that is properly maintained in accordance with NFPA 25 and has not undergone substantial modification defined within 310 CMR 22.22(9)(d)3. Alarm check maintenance records must be available for inspection by the Department, its designee or the public water system
(b) Class 2: Same as Class 1 except that booster pumps may be installed in the connections from the street mains These systems may or may not have fire department connections. Refer to 310 CMR 22.22(9)(a).	X	X	X	A backflow prevention assembly does not have to be installed on existing fire protection system installed prior to March 21, 1997, provided that the fire protection system is registered with the public water system and equipped with a UL listed alarm check valve that is properly maintained in accordance with NFPA 25. Alarm check maintenance records must be available for inspection by the Department, its designee or the public water system.
(c) Class 3: Direct connection from public water system mains, plus one or more of the following: elevated storage tanks; fire pumps taking suction from aboveground covered reservoirs, or tanks; and pressure tanks.	X	X*	X*	*RPBP or DCVA contingent on evaluation of auxiliary supply and on-site system in accordance with 310 CMR 22.22(9)(d)1.
(d) Class 4: Directly supplied from public water system mains, similar to Class 1 and Class 2 with an auxiliary water supply dedicated to fire department use and available to the premises, such as a non-potable water source located within 1700 feet of the fire department connection, (FDC).	X	X*	*RPBP on evaluation of auxiliary supply and onsite system in accordance with 310 CMR 22.22(9)(d)1.
(e) Class 5: Directly supplied from public water system mains, and interconnected with auxiliary supplies, such as pumps taking suction from reservoirs exposed to contamination, or rivers and ponds; driven wells; mills or other industrial water systems; or where antifreeze or other additives are used.	X*	X*	*RPBP or air gap contingent on evaluation of auxiliary supply and on-site system. Refer to 310 CMR 22.22(9)(d)1.
(f) Class 6: Combined industrial and fire protection systems supplied from the public water mains only, with or without gravity storage or pump suction tanks.	X	X*	X	X	*RPBP contingent on evaluation of on-site water system. Refer to 310 CMR 22.22 (9)(d)1.
(g) Residential fire protection systems for one and two family detached dwellings and manufactured homes only. Fire protection systems in three family dwellings meeting NFPA 13D requirements as provided in 780 CMR, Chapter 9, are included in this section.	X	X	X	Fire protection system in this category shall comply with the requirements set forth in class 1 through 4 as appropriate.
20. Solar Energy Systems	X	X	X*	Residential and small commercial having no chemicals or only USP Glycine added to water
21. Single Jacketed Heat Exchangers	X	X	Each case should be evaluated individually

Source of Table 8A is Department of Environmental Protection (DEP) 310 CMR 22.22(c)

248 CMR, § 10.14

Amended by Mass Register Issue 1331, eff. 1/27/2017.

Amended by Mass Register Issue 1510, eff. 12/8/2023.