Whenever the Plumbing Inspector determines that it is not practical
to protect drinking water systems on premises against entry of water
from a source or piping system or equipment that cannot be approved
as safe or potable for human use, an entirely separate drinking water
system shall be installed to supply water at points convenient for
consumers.
Water systems, for fighting fire, derived from a supply that
cannot be approved as safe or potable for human use or to which chemicals
are added shall, wherever practicable, be kept wholly separate from
drinking water pipelines and equipment. In cases where the domestic
water system is used for both drinking and fire-fighting purposes,
approved backflow prevention devices shall be installed to protect
such individual drinking water lines as are not used for fire-fighting
purposes.
Potable water pipelines connected to equipment for industrial
processes or operations shall be protected by a suitable backflow
prevention device located beyond the last point from which drinking
water may be taken, which device shall be provided on the feed line
to process piping or equipment. In the event that the particular process
liquid is especially corrosive or apt to prevent reliable action of
the backflow prevention device, air-gap separation shall be provided.
These devices shall be tested by the water user at least once a year
or more often in those instances where successive inspections indicate
repeated failure. The devices shall be repaired, overhauled or replaced
whenever they are found to be defective. These tests must be performed
by a qualified backflow prevention device tester, and records of tests,
repairs and replacement shall be kept and made available to the water
purveyor and the Health Department upon request.
Sewage pumps shall not have priming connections directly off
any drinking water systems. No connections shall exist between the
drinking water system and any other piping, equipment or tank in any
sewage treatment plant or sewage pumping station.
A.
Where the circumstances are such that there is special danger to
health by the backflow of sewage, as from sewers, toilets, hospital
bedpans and the like, into a drinking water system, a dependable device
or devices shall be installed to prevent such backflow.
B.
The purpose of this chapter is not to transcend local plumbing regulations,
but only to deal with those extraordinary situations where sewage
may be forced or drawn into the drinking water piping. This chapter
do not attempt to eliminate at this time the hazards of back-siphonage
through flushometer valves on all toilets, but to deal with those
situations where the likelihood of vacuum conditions in the drinking
water system is definite and there is special danger to health. Devices
suited to the purpose of avoiding back-siphonage from plumbing fixtures
are roof tanks, barometric loops or separate pressure systems separately
piped to supply such fixtures, recognized approved vacuum or siphon
breaker and other backflow protective devices which have been proved
by appropriate tests to be dependable for destroying the vacuum.
C.
Inasmuch as many of the serious hazards of this kind are due to water
supply piping which is too small, thereby causing vacuum conditions
when fixtures are flushed or water is drawn from the system in other
ways, it is required that water supply piping that is too small be
enlarged whenever possible.
Backflow protection by a suitable backflow prevention device
shall be provided on each drinking water pierhead outlet used for
supplying vessels at piers or waterfronts. These assemblies must be
located where they will prevent the return of any water from the vessel
into the drinking water pipeline or into another adjacent vessel.
This will prevent such practices as connecting the ship fire-pumping
or sanitary-pumping system with a dock hydrant and thereby pumping
contaminated water into the drinking water system and thence to adjacent
vessels or back into the public mains.
Where the premises contain dual or multiple water systems and
piping, the exposed portions of pipelines shall be painted, banded
or marked at sufficient intervals to distinguish clearly which water
is safe and which is not safe. All outlets from secondary or other
potentially contaminated systems shall be posted as being contaminated
and unsafe for drinking purposes. All outlets intended for drinking
purposes shall be plainly marked to indicate that fact.
