| (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 firefighting
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, defined in TWC §13.1394 or §13.1395, must be
designed to meet the requirements of §290.45(h) or (i) 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.
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