Enable Master Valve for specific zones

I want to inject mosquito chemicals into the backyard zones only.
Others have already requested a software change to be able to enable the master valve/pump for specific zones. The 1st request was in 2014.


What kind of backflow device is installed on your sprinkler system?

Not sure. House was built in 2004
What are your thoughts?

Once you integrate chemicals into the sprinkler lines water, you’ve just created a high hazard cross connection. Any high hazard cross connection requires a reduced pressure principle device (RPZ) for the backflow connection to the supply. All backflow installation requirements are based on a potential backflow situation whether it ever happens or not.

If you are connected to a public water supply, and even if you’re not, ask them their position on adding chemicals into your sprinkler system.

I wouldn’t do it for that reason alone. But what about another scenario: Your kiddos, neighbors, or animals happen to be in that mosquito chemicals area and the zone came on by accident and sprayed them? Or the zone stuck open and now your chemical run off is flooding your neighbors lawn, going down the street into the gutter that goes to a local creek?

Just throwing stuff out to think about. I hate mosquitos too!

Have a great day!


With the ability to control the master valve for s specific schedule there will not be any overflow. Also I live in the country with acreage.
What is the eta for this much needed improvement.
I don’t want to drag my old Weathermatic out.

@Rayics - not to diminish what @Sprinlerman says as I think I remember an old episode of Emergency! where a crew was flushing a gas line with domestic water and there was no backflow preventer which allowed the gas to go into the water line and caught a toilet on fire when someone threw away a lit cigarette.

Anyway I digress. A possible solution would be to put a NO DPDT 24 VAC relay (normally open, double pole double throw 24 V AC coil) on each zone where you want the chemicals injected. The Rachio zone would be connected to the relay coil, one of the poles on the relay would be connected to the sprinkler system soleniod (which is currently connected directly to the Rachio) and the other pole would connect with the pump start relay that would power the injection system. The power for the poles would come from the master pump connection which would need to be turned on all the time. For a similar set up see -> Run Multiple Zones At Once

Just remember that there will still be chemicals in the line after the injection point so they will sit there in the pipe until the next run - corrosion or settling out and sticking or clogging things up. This would be the main line, so the next zone would get some chemicals and in the valve, sprinker and zone piping for the selected zone(s). Even if you’re out in the country on your own water system, the chemicals could come back around the corner into your potable water supply. So unless your sprinkler system is on a separate water source than your potable water, I’d also second the backflow preventer device.


Thanks for your quick reply.

I really don’t want a bunch of additional electronics to maintain.

I have a very stout back flow preventer.
The mosquito chemical is basically a garlic derivative … could probably drink it.

I was planning to turn on the master pump for a few minutes, for a few valves on a separate schedule.

I live in a HOA with over 1,000 homes and we have over six lakes (mosquito haven). I was going to email all of the homeowners how to use a Rachio to control mosquitoes.

I develop software for a living (C#, C++, JavaScript, Java) and know how simple this enhancement would be to make. I also understand limited resources and allocating those resources to the enhancements that will bring in the most revenue. I was hoping Rachio could allocate a few days to such a simple enhancement.

@Rayics - I understand. The relay is sealed and dead simple, so not really adding much electronics.