HighqualityPlumbing
Member
I have a gravity based greywater system that is fed from a rain barrel with water level about 3-6 feet above ground. The rain barrel has an inlet from the roof gutters, as well as from the laundry machine. (Biodegradable detergents will be used when the laundry water is used for greywater.)
I wish to have a switchover (ball valves) that would enable me to switch the irrigation system "inlet" between greywater and city water, depending on greywater availability (or lack thereof), by switching two ball valves (closing one and opening the other). The ball valves would be situated between the rain barrel and a central main irrigation line "inlet", and between a garden faucet and the irrigation lines, respectively.
I am aware that because of the greatly different pressure of the gravity fed water and the pressurized water lines, any control valves or outlet valves would probably have to be manually operated if the same drip lines were to be used in either case, and I am aware of the special requirements for irrigation lines and emitters of gravity based drip irrigation. The objective however is to have a drip irrigation system that can be fed from either greywater or pressurized water depending on needs, or the season, and to have water outlets available in the various places in the yard without having to carry around water hoses, rather than fully automated timer valves.
A backflow preventer is required to prevent backflow from the irrigation water to the potable water lines. Since the rain barrel is naturally higher than the rest of the irrigation system, it would be difficult to install the backflow preventer at a location above the rain barrel. Is it correct that a reduced pressure zone assembly (e.g. Watts 009) is required for this situation?
Is it correct that a double check valve assembly is not appropriate?
Can a pressure vacuum breaker be used? I am aware that by the letter of the law, a PVB can not be used when sprinkler heads or plumbing is higher than the PVB (although some references only mention sprinkler heads/outlets, not plumbing in between). But in this scenario, there would never be any direct connection between the rain barrel and the potable water, but only between the potable water and downstream irrigation lines which are all lower than the backflow preventer. Thus there would never be gravity or other back pressure possible.
Independently of this, I got conflicting information as to whether or not a PVB can be used for "hazardous" applications (even if all plumbing is 12'' lower than the PVB), and what exactly constitutes "hazardous" vs. "contaminated" vs. "polluted". Please advise.
Lastly, I am not too concerned about local codes or enforcement or lack thereof, but rather the reasoning and rationale behind the code(s), as well as actual safety considerations and functioning of the various backflow prevention methods.
I wish to have a switchover (ball valves) that would enable me to switch the irrigation system "inlet" between greywater and city water, depending on greywater availability (or lack thereof), by switching two ball valves (closing one and opening the other). The ball valves would be situated between the rain barrel and a central main irrigation line "inlet", and between a garden faucet and the irrigation lines, respectively.
I am aware that because of the greatly different pressure of the gravity fed water and the pressurized water lines, any control valves or outlet valves would probably have to be manually operated if the same drip lines were to be used in either case, and I am aware of the special requirements for irrigation lines and emitters of gravity based drip irrigation. The objective however is to have a drip irrigation system that can be fed from either greywater or pressurized water depending on needs, or the season, and to have water outlets available in the various places in the yard without having to carry around water hoses, rather than fully automated timer valves.
A backflow preventer is required to prevent backflow from the irrigation water to the potable water lines. Since the rain barrel is naturally higher than the rest of the irrigation system, it would be difficult to install the backflow preventer at a location above the rain barrel. Is it correct that a reduced pressure zone assembly (e.g. Watts 009) is required for this situation?
Is it correct that a double check valve assembly is not appropriate?
Can a pressure vacuum breaker be used? I am aware that by the letter of the law, a PVB can not be used when sprinkler heads or plumbing is higher than the PVB (although some references only mention sprinkler heads/outlets, not plumbing in between). But in this scenario, there would never be any direct connection between the rain barrel and the potable water, but only between the potable water and downstream irrigation lines which are all lower than the backflow preventer. Thus there would never be gravity or other back pressure possible.
Independently of this, I got conflicting information as to whether or not a PVB can be used for "hazardous" applications (even if all plumbing is 12'' lower than the PVB), and what exactly constitutes "hazardous" vs. "contaminated" vs. "polluted". Please advise.
Lastly, I am not too concerned about local codes or enforcement or lack thereof, but rather the reasoning and rationale behind the code(s), as well as actual safety considerations and functioning of the various backflow prevention methods.
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