| (a) Design and standards. All potable water distribution
systems including pump stations, mains, and both ground and elevated
storage tanks, shall be designed, installed, and constructed in accordance
with current American Water Works Association (AWWA) standards with
reference to materials to be used and construction procedures to be
followed. In the absence of AWWA standards, commission review may
be based upon the standards of the American Society for Testing and
Materials (ASTM), commercial, and other recognized standards utilized
by licensed professional engineers.
(1) All newly installed pipes and related products
must conform to American National Standards Institute/NSF International
(ANSI/NSF) Standard 61 and must be certified by an organization accredited
by ANSI.
(2) All plastic pipes for use in public water systems
must also bear the NSF International Seal of Approval (NSF-pw) and
have an ASTM design pressure rating of at least 150 pounds per square
inch (psi) or a standard dimension ratio of 26 or less.
(3) No pipe which has been used for any purpose other
than the conveyance of drinking water shall be accepted or relocated
for use in any public drinking water supply.
(4) Water transmission and distribution lines must
be installed in accordance with the manufacturer's instructions. However,
the top of the waterline must be located below the frost line and
in no case shall the top of the waterline be less than 24 inches below
ground surface.
(5) The hydrostatic leakage rate shall not exceed the
amount allowed or recommended by AWWA formulas.
(b) Lead ban. The following provisions apply to the
use of lead in plumbing.
(1) The use of pipes and pipe fittings that contain
more than 0.25% lead or solders and flux that contains more than 0.2%
lead is prohibited in the following circumstances:
(A) for installation or repair of any public water
supply; and
(B) for installation or repair of any plumbing in a
residential or nonresidential facility providing water for human consumption
and connected to a public drinking water supply system.
(2) This requirement will be waived for lead joints
that are necessary for repairs to cast iron pipe.
(3) The following are exempt from prohibitions on the
use of lead pipes, solder, and flux:
(A) pipes, pipe fittings, plumbing fittings, or fixtures,
including backflow preventers, that are used exclusively for nonpotable
services such as manufacturing, industrial processing, irrigation,
outdoor watering, or any other uses where the water is not anticipated
to be used for human consumption; or
(B) toilets, bidets, urinals, fill valves, flush-o-meter
valves, tub fillers, shower valves, service saddles, fire hydrants
or water distribution main gate valves that are two inches in diameter
or larger.
(c) Minimum waterline sizes. The minimum waterline
sizes are for domestic flows only and do not consider fire flows.
Larger pipe sizes shall be used when the licensed professional engineer
deems it necessary. It should be noted that the required sizes are
based strictly on the number of customers to be served and not on
the distances between connections or differences in elevation or the
type of pipe. No new waterline less than two inches in diameter will
be allowed to be installed in a public water system distribution system.
These minimum line sizes do not apply to individual customer service
lines.
Attached Graphic
(d) Minimum pressure requirement. The system must be
designed to maintain a minimum pressure of 35 psi at all points within
the distribution network at flow rates of at least 1.5 gallons per
minute per connection. When the system is intended to provide fire
fighting capability, it must also be designed to maintain a minimum
pressure of 20 psi under combined fire and drinking water flow conditions.
The distribution system of public water systems that are also affected
utilities must be designed to meet the requirements of §290.45(h)
of this title (relating to Minimum Water System Capacity Requirements).
(1) Air release devices shall be installed in the distribution
system at all points where topography or other factors may create
air locks in the lines. Air release devices shall be installed in
such a manner as to preclude the possibility of submergence or possible
entrance of contaminants. In this respect, all openings to the atmosphere
shall be covered with 16-mesh or finer, corrosion-resistant screening
material or an acceptable equivalent.
(2) When service is to be provided to more than one
pressure plane or when distribution system conditions and demands
are such that low pressures develop, the method of providing increased
pressure shall be by means of booster pumps taking suction from storage
tanks. If an exception to this requirement is desired, the designing
engineer must furnish for the executive director's review all planning
material for booster pumps taking suction from other than a storage
tank. The planning material must contain a full description of the
supply to the point of suction, maximum demands on this part of the
system, location of pressure recorders, safety controls, and other
pertinent information. Where booster pumps are installed to take suction
directly from the distribution system, a minimum residual pressure
of 20 psi must be maintained on the suction line at all times. Such
installations must be equipped with automatic pressure cut-off devices
so that the pumping units become inoperative at a suction pressure
of less than 20 psi. In addition, a continuous pressure recording
device may be required at a predetermined suspected critical pressure
point on the suction line in order to record the hydraulic conditions
in the line at all times. If such a record indicates critical minimum
pressures, less than 20 psi, adequate storage facilities must be installed
with the booster pumps taking suction from the storage facility. Fire
pumps used to maintain pressure on automatic sprinkler systems only
for fire protection purposes are not considered as in-line booster
pumps.
(3) Service connections that require booster pumps
taking suction from the public water system lines must be equipped
with automatic pressure cut-off devices so that the pumping units
become inoperative at a suction pressure of less than 20 psi. Where
these types of installations are necessary, the preferred method of
pressure maintenance consists of an air gapped connection with a storage
tank and subsequent repressurization facilities.
(4) Each community public water system shall provide
accurate metering devices at each residential, commercial, or industrial
service connection for the accumulation of water usage data. A water
system that furnishes the services or commodity only to itself or
its employees when that service or commodity is not resold to or used
by others is exempt from this requirement.
(5) The system shall be provided with sufficient valves
and blowoffs so that necessary repairs can be made without undue interruption
of service over any considerable area and for flushing the system
when required. The engineering report shall establish criteria for
this design.
(6) The system shall be designed to afford effective
circulation of water with a minimum of dead ends. All dead-end mains
shall be provided with acceptable flush valves and discharge piping.
All dead-end lines less than two inches in diameter will not require
flush valves if they end at a customer service. Where dead ends are
necessary as a stage in the growth of the system, they shall be located
and arranged to ultimately connect the ends to provide circulation.
(e) Location of waterlines. The following rules apply
to installations of waterlines, wastewater mains or laterals, and
other conveyances/appurtenances identified as potential sources of
contamination. Furthermore, all ratings specified shall be defined
by ASTM or AWWA standards unless stated otherwise. New mains, service
lines, or laterals are those that are installed where no main, service
line, or lateral previously existed, or where existing mains, service
lines, or laterals are replaced with pipes of different size or material.
(1) When new potable water distribution lines are constructed,
they shall be installed no closer than nine feet in all directions
to wastewater collection facilities. All separation distances shall
be measured from the outside surface of each of the respective pieces.
(2) Potable water distribution lines and wastewater
mains or laterals that form parallel utility lines shall be installed
in separate trenches.
(3) No physical connection shall be made between a
drinking water supply and a sewer line. Any appurtenance shall be
designed and constructed so as to prevent any possibility of sewage
entering the drinking water system.
(4) Where the nine-foot separation distance cannot
be achieved, the following criteria shall apply.
(A) New waterline installation - parallel lines.
(i) Where a new potable waterline parallels an existing,
non-pressure or pressure rated wastewater main or lateral and the
licensed professional engineer licensed in the State of Texas is able
to determine that the existing wastewater main or lateral is not leaking,
the new potable waterline shall be located at least two feet above
the existing wastewater main or lateral, measured vertically, and
at least four feet away, measured horizontally, from the existing
wastewater main or lateral. Every effort shall be exerted not to disturb
the bedding and backfill of the existing wastewater main or lateral.
(ii) Where a new potable waterline parallels an existing
pressure-rated wastewater main or lateral and it cannot be determined
by the licensed professional engineer if the existing line is leaking,
the existing wastewater main or lateral shall be replaced with at
least 150 psi pressure-rated pipe. The new potable waterline shall
be located at least two feet above the new wastewater line, measured
vertically, and at least four feet away, measured horizontally, from
the replaced wastewater main or lateral.
(iii) Where a new potable waterline parallels a new
wastewater main, the wastewater main or lateral shall be constructed
of at least 150 psi pressure-rated pipe. The new potable waterline
shall be located at least two feet above the wastewater main or lateral,
measured vertically, and at least four feet away, measured horizontally,
from the wastewater main or lateral.
(B) New waterline installation - crossing lines.
(i) Where a new potable waterline crosses above a wastewater
main or lateral, the segment of the waterline pipe shall be centered
over and must be perpendicular to the wastewater main or lateral such
that the joints of the waterline pipe are equidistant and at least
nine feet horizontally from the centerline of the wastewater main
or lateral. When crossing an existing wastewater main or lateral and
it is disturbed or shows signs of leaking, the wastewater main or
lateral shall be replaced for at least nine feet in both directions
(18 feet total) with at least 150 psi pressure-rated pipe embedded
in cement stabilized sand (see clause (v) of this subparagraph) for
the total length of one pipe segment plus 12 inches beyond the joint
on each end.
(I) The potable waterline shall be at least two feet
above an existing, non-pressure rated wastewater main or lateral.
(II) The potable waterline shall be at least six inches
above an existing, pressure-rated wastewater main or lateral.
(ii) Where a new potable waterline crosses a new, non-pressure
rated wastewater main or lateral, the segment of the waterline pipe
shall be centered over and shall be perpendicular to the wastewater
main or lateral such that the joints of the waterline pipe are equidistant
and at least nine feet horizontally from the centerline of the wastewater
main or lateral. The potable waterline shall be at least two feet
above the wastewater main or lateral. Whenever possible, the crossing
shall be centered between the joints of the wastewater main or lateral.
The wastewater pipe shall have a minimum pipe stiffness of 115 psi
at 5.0% deflection. The wastewater main or lateral shall be embedded
in cement stabilized sand (see clause (v) of this subparagraph) for
the total length of one pipe segment plus 12 inches beyond the joint
on each end. The materials and method of installation shall conform
to one of the following options:
(I) Within nine feet horizontally of either side of
the waterline, the wastewater pipe and joints shall be constructed
with pipe material having a minimum pressure rating of at least 150
psi. An absolute minimum vertical separation distance of two feet
shall be provided. The wastewater main or lateral shall be located
below the waterline.
(II) All sections of wastewater main or lateral within
nine feet horizontally of the waterline shall be encased in an 18-foot
(or longer) section of pipe. Flexible encasing pipe shall have a minimum
pipe stiffness of 115 psi at 5.0% deflection. The encasing pipe shall
be centered on the waterline and shall be at least two nominal pipe
diameters larger than the wastewater main or lateral. The space around
the carrier pipe shall be supported at five-foot (or less) intervals
with spacers or be filled to the springline with washed sand. Each
end of the casing shall be sealed with watertight non-shrink cement
grout or a manufactured watertight seal. An absolute minimum separation
distance of six inches between the encasement pipe and the waterline
shall be provided. The wastewater line shall be located below the
waterline.
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