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 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 waterlines 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.
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.