Hi, Sorry! I've been laying out my tubing, and figuring out 1/2" tubes also come in 1/2" ID sizes. Back & forth to the store for different sized adaptors ... I have a 25 psi regulator on the water source set-up. I'll also get a pressure gauge, you're right, it would be good to know the pressure to the house anyway. I never thought about the flow rate ... I'll measure it all in a bucket before I start actually watering - jeez! Sort of important - thank you. :) I have 4 - 1/2" hoses, with no more than 40' or so of each. They will each have varying lengths of 1/4" hose running off them, no more than 10-12'. I have several 1 GPH heads along each hose, most at least 18" or so. Only one 1/2" hose station, the one for the shaded bed where the valves are located, will have heads running directly off of it, but only 8 or so; it's not a long line. So, just to be clear - I add the # of GPH's, and they need to be under 80% of hose bib total ... I've got some calculating to do! I'll be running each station for a different length of time, for a different # of days (vines vs. succulents vs. shade, etc). I have 153 plants so far, so I've already exceeded that, right? I'll have to water on different days. I'm not setting up the anti-syphon valve system, including attaching my hose to a separate valve, until I have the irrigation hoses all laid out and working, and the watering timed right, just to be safe. The current manual set-up is cheap enough, although not very sturdy, and my kitchen timer goes up to 9 hours. I don't even have my shaded bed planted yet; I'll wait for the permanent valve set-up (so I know what I have to hide). When I do get it set up, then I'll add the multi-station timer to work with the solenoid/anti-syphon valves, and the kitchen timer won't be used any more. It'll work for this manual system for now, so when 1 station is done being watered, I can turn off that valve, and then the next valve can be shut off when that's done and so on - that is if they're all being watered at the same time, which I don't think I can do with the pressure issue. OK, I'm off to finish the hoses and do some math - I always liked a good word problem! Thank you!

Lazypup -- I found this tempering valve. The "L" version says it can temper between 60 and 120. Any reason you see that I couldn't use this for my purposes? Also, can one put a shut-off valve on the hot water side and still have these work? I don't really need the water to be 60 degrees in the summer (assuming cold water is below 60). Here is a link that might be useful: Watts L1170

You can purchase add-on ball valve fittings for turning the flow down. You probably already have ball valves inside the house for turning the water off in winter. These are 1/4 turn valves but if you can not turn them 1/8 turn (click open / click closed), then you can try the add on ball valve outside instead of replacement. You should be able to get them at Lowes or another garden center.

Creative thinking, I like that. The only thing I would add to your setup is a vacuum breaker such as this: https://www.homedepot.com/p/Everbilt-3-4-in-Hose-Bibb-Vacuum-Breaker-VACBFPZ4EB/205815672 Plumbing codes require and air breaker whenever dealing with a potable drinking water supply which could be connected to a non-potable water source (which I presume your garden fountain would be!). The thinking is that if the house water supply ever fails and develops a suction, the non-potable water could be pulled into and contaminate the potable house water. Not good. The vacuum breaker prevents this situation from ever happening, it's cheap insurance. Install the breaker between the timer outlet and the line going to the fountain. The hose bib timer I'm envisioning is those that might be battery operated and used for small drip irrigation setups, like this:. https://www.amazon.com/Orbit-62061Z-Single-Programmable-1-Valve/dp/B004INGS8S/ref=zg_bs_553988_1?_encoding=UTF8&psc=1&refRID=PPVK6RY4NB7N6K8WS340 If that is true, I wouldn't worry about leaving the water pressure on over extended periods, they're intended for that type of use. Give the bath a few minutes of water every day and enjoy! I like that.