I found a good liquid repellant, that does a fair job, whose primary ingredient is garlic. Aside from smelling somewhat like an Italian eatery it does work well for a few days at a time, but distribution can take a while. Using a hand feeder attached to my garden hose to spray the mixture is slow if I want to ensure the yard is covered.
Then I saw that my lawn sprinklers cover the entire place, quickly, and decided to attempt running the mixture through them. I've seen systems online sold for $1400+. I did mine for less than $30.
The idea was to steal the water from my backflow preventer, route it through the "venturi" feeder to collect the garlic mixture, and then join back up with the original outbound line to the sprinkler zones. I had to be able to shut this off and on, both to water my lawn as well as purge the mixture from the lines which only takes a few minutes. I started with this assembly which came with the house. There is a black sprinkler head in front which unfortunately is in the way of the lower ball valve in the photos, but the fence turns and this angle was the best I could do.
Unlike some feeders which use a straw to collect the mixture, this one has two orifices of different sizes: the smaller one is used to fill and pressurize the reservoir; the larger one is the "venturi" orifice to pull the mixture out.
Once the reservoir is filled the output lists as 3 tbsp per gallon of water. I'm currently testing the zones to see what the rates of depletion are.
Step 1: Parts & tools
(3) 1" PVC ball vales;
(2) 1" PVC elbows (90s)
(2) 1" PVC T-fittings (slip). I used one with a side-out as I had to turn a corner close to my fence line.
(1) 5ft length of 1" PVC (sched 40). I had quite a bit left over.
(2) Hose adapters: 3/4" threaded to 1" PVC (need male & female threads)
(1) brick or block of wood.
(1) 3" PVC coupler
(1) 3" PVC to 1" adapter
(1) 3" threaded PVC cap
(1) 1 1/2 " to 1" PVC Wye adapter
The last four items were swapped in place of the plastic feeder from the earlier version. That is the blurred portion of the image.
Channel lock pliers