Um,
I'm just north of you in the Belton/Temple area and in the process of building a pool. My PB didn't kick back the idea of tying into my irrigation system, but when I started doing my own research I found some TCEQ regulations that prevented doing exactly that:
- TCEQ’s Landscape Irrigation regulations prohibit a connection to be made to the irrigation system. This is stated in 30 TAC 344.62
Water contained within the piping of an irrigation system is deemed to be non-potable. No drinking or domestic water usage, such as, but not limited to, filling swimming pools or decorative fountains, shall be connected to an irrigation system. If a hose bib (an outdoor water faucet that has hose threads on the spout) is connected to an irrigation system for the purpose of providing supplemental water to an area, the hose bib must be installed using a quick coupler key on a quick coupler installed in a covered purple valve box and the hose bib and any hoses connected to the bib must be labeled "non-potable, not safe for drinking." An isolation valve must be installed upstream of a quick coupler connecting a hose bib to an irrigation system.
- Per the Swimming Pool Code (SPC) the swimming pool must be filled with potable water.
(https://www.tceq.texas.gov/assets/public/permitting/watersupply/groups/ccc/finalsummary20120904.pdf)
The air gap for your fill line only prevents chemicals in the pool from siphoning back into the system. Tying into the irrigation system can still potentially siphon lawn chemicals, pet waste, etc. from the rest of your irrigation system into your pool. Did you not have any issues outside of what you already mentioned getting the system installed and past inspections? Only way I see to do it by the regulations is to tap off the house main line and install an approved back flow (or possibly just have the inlet above the coping like you have) to fill your pool with potable water and not have a chance for cross-contamination between the pool, public water supply, or irrigation system.