Landscape Irrigation
City Water Main - answer Although not all irrigation systems use municipal water, for
residential landscape this is usually the case. The city water main is often a 4" pipe that
is tapped for private use.
Water purveyor's valve - answer A manual valve on or near the water meter.
Water Meter - answer A mechanical device used to measure the volume of water being
used. The city usually owns up to and including the water meter and the homeowner
usually owns everything past the water meter.
The water meter is usually just a few feet from the city's mainline.
Note that when one calls for a utility locate the city will mark the main and perhaps to
the water meter but they will not locate beyond the water meter because that is the
owner's property. The service line will not get located.
Service line - answer Usually a PVC line between the water meter and the point of
connection (POC), the point where the irrigation contractor starts the irrigation system.
Back pressure - answerPressure is created upstream by an elevation change or a pump
that could cause the water to flow back into the city's main.
POC - answerThe point of connection, where the irrigation system starts. POC is a
commonly used abbreviation.
Backflow Prevention Device - answerA mechanical device used to prevent potentially
contaminated water from flowing out of the irrigation system and back into the potable
water system. Backflow can occur due to back pressure or back siphonage.
Back siphonage - answerA water main break or other cause of high flow creates a
vacuum siphoning water out of the irrigation system and into the main.
Backflow is a very serious issue and is usually covered by local, state, and/or federal
codes.
Some backflow prevention devices must be installed by licensed plumbers. - answertrue
Air Gap - answernot often used in residential landscapes but could be used where a
private water source is supplemented by a municipal water source.
Vacuum Breakers - answerProtect only against back siphonage. Do not protect against
back pressure.
, Two types
Atmospheric Vacuum Breakers - answerType of Vacuum Breaker:
are not designed to have constant pressure downstream therefore the valve must be
before the device.
Therefore they are not usually used on multi-zone irrigation systems.
Pressure Vacuum Breakers - answerType of Vacuum Breaker:
so called (pressure) because the downstream side can be pressurized allowing for
multiple valves. This is by far the most commonly used backflow prevention device for
residential irrigation systems.
Reduced Pressure Assembly - answerprotects against back siphonage and back
pressure.
This is the only backflow prevention device allowed if the water outlet will be higher than
the backflow device or if chemicals are to be injected in the system.
This is the device to use in greenhouse applications.
Double Check Valve - answerno longer meets code for irrigation systems.
Descriptions of AVB - Atmospheric Vacuum Breaker backflow prevention devices from
City of Stillwater's Development Services Information Guide: - answerOne required for
each irrigation zone; no control valves (on/off valves) allowed downstream of (after)
one.
Each one must be installed a minimum of six inches (6") above the highest point of
water in the zone it serves.
No chemical or fertilizer may be introduced into an irrigation system equipped with one
installed
No pumps or back pressure on downstream side of (after) an one
They do not have to be installed by licensed plumbers or inspected
Descriptions of PVB Vacuum Breaker backflow prevention devices from City of
Stillwater's Development Services Information Guide: - answerOnly one required to
serve the whole system; control valves can be located downstream of (after) one.
Must be installed a minimum of one foot (12") above the highest point of water they
serve.
Must be tested by a State-certified Backflow Assembly Tester... when installed...
annually...when moved or repaired.
City Water Main - answer Although not all irrigation systems use municipal water, for
residential landscape this is usually the case. The city water main is often a 4" pipe that
is tapped for private use.
Water purveyor's valve - answer A manual valve on or near the water meter.
Water Meter - answer A mechanical device used to measure the volume of water being
used. The city usually owns up to and including the water meter and the homeowner
usually owns everything past the water meter.
The water meter is usually just a few feet from the city's mainline.
Note that when one calls for a utility locate the city will mark the main and perhaps to
the water meter but they will not locate beyond the water meter because that is the
owner's property. The service line will not get located.
Service line - answer Usually a PVC line between the water meter and the point of
connection (POC), the point where the irrigation contractor starts the irrigation system.
Back pressure - answerPressure is created upstream by an elevation change or a pump
that could cause the water to flow back into the city's main.
POC - answerThe point of connection, where the irrigation system starts. POC is a
commonly used abbreviation.
Backflow Prevention Device - answerA mechanical device used to prevent potentially
contaminated water from flowing out of the irrigation system and back into the potable
water system. Backflow can occur due to back pressure or back siphonage.
Back siphonage - answerA water main break or other cause of high flow creates a
vacuum siphoning water out of the irrigation system and into the main.
Backflow is a very serious issue and is usually covered by local, state, and/or federal
codes.
Some backflow prevention devices must be installed by licensed plumbers. - answertrue
Air Gap - answernot often used in residential landscapes but could be used where a
private water source is supplemented by a municipal water source.
Vacuum Breakers - answerProtect only against back siphonage. Do not protect against
back pressure.
, Two types
Atmospheric Vacuum Breakers - answerType of Vacuum Breaker:
are not designed to have constant pressure downstream therefore the valve must be
before the device.
Therefore they are not usually used on multi-zone irrigation systems.
Pressure Vacuum Breakers - answerType of Vacuum Breaker:
so called (pressure) because the downstream side can be pressurized allowing for
multiple valves. This is by far the most commonly used backflow prevention device for
residential irrigation systems.
Reduced Pressure Assembly - answerprotects against back siphonage and back
pressure.
This is the only backflow prevention device allowed if the water outlet will be higher than
the backflow device or if chemicals are to be injected in the system.
This is the device to use in greenhouse applications.
Double Check Valve - answerno longer meets code for irrigation systems.
Descriptions of AVB - Atmospheric Vacuum Breaker backflow prevention devices from
City of Stillwater's Development Services Information Guide: - answerOne required for
each irrigation zone; no control valves (on/off valves) allowed downstream of (after)
one.
Each one must be installed a minimum of six inches (6") above the highest point of
water in the zone it serves.
No chemical or fertilizer may be introduced into an irrigation system equipped with one
installed
No pumps or back pressure on downstream side of (after) an one
They do not have to be installed by licensed plumbers or inspected
Descriptions of PVB Vacuum Breaker backflow prevention devices from City of
Stillwater's Development Services Information Guide: - answerOnly one required to
serve the whole system; control valves can be located downstream of (after) one.
Must be installed a minimum of one foot (12") above the highest point of water they
serve.
Must be tested by a State-certified Backflow Assembly Tester... when installed...
annually...when moved or repaired.
