Everything from the chat, in one place — how the diverter feeds your barrel, sends the overflow back down the spout, and exactly which couplings do the work.
Rain off your privacy-wall gutter drops down the downspout, the RainReserve skims part of it into the barrel, and excess pours back down the spout to grade — three floors down.
Diverter to barrel is just a chain of six pieces. Only the first joint is unusual — the rest is standard hardware. The coloured tag on each shows how it seals.
The single make-or-break rule: the printed spout is PETG — PVC cement won't bond it. Scuff it, bed it in 100% silicone, push the valve socket on (it only seats partway because the spout is short — that's normal), cure 24 h. Every joint after that seals the normal way.
It's gravity, near-zero pressure. Each point just has to sit lower than the one above it. You've got ~6'2" of downspout to play with, so it lays out easily.
Your barrel is small, so it'll sit full and the overflow does most of the work. ¾" overflow matches your ¾" feed — fine, but keep it clear and upsize if it ever backs up at the lid.
Overflow returns into the downspout — never spill off the deck edge onto neighbours below. The spout carries it safely to grade.
Tap the downspout pipe, not the trough on the wall — gravity can't lift overflow back up there.
What you already have, what's left to grab, and what's for the irrigation phase later. Filter below.
The reservoir. Gasketed lid lifts for access.
Diverter shut-off. Double slip socket — spout slides in.
Barrel thru-wall: one inlet, one overflow.
The feed line, diverter → barrel.
Top, bottom, basket, diverter, 4×3 supports.
The one bridge from valve outlet to hose thread.
Seals the printed-spout joint (cure 24h).
Over the lid inlet — standing water breeds bugs.
Bottom draw-off spigot, for the irrigation side.
Smart hose-thread timer for drip control.
Lines + emitters out to the pots.
Per-pot moisture, threshold watering.
A sealed inlet means matching thread gender. A hose has one male + one female end, so the two things it connects to must be opposite. Tap your answer:
Take your hose's male end (plain threads, no spinning collar) and try it on the inlet bulkhead's outer port…
Do the cement/threaded joints first and let them set. Save the silicone spout joint for last so it cures undisturbed.
Cut the downspout so the RainReserve outlet lands 6–12" above the barrel lid (220 mm / 8-11/16" section out).
Mount the Top + Bottom + 4×3 supports; leave room above so the top slides up to clean the basket.
Glue the slip × MHT adapter into the valve's outlet socket (PVC primer + cement).
Drill + fit the bulkheads — inlet high on the barrel, overflow 1–2" below it, gasket on a flat spot, hand-tight + ¼ turn.
Run the hoses — feed: valve → barrel inlet; overflow: barrel → downspout tap (angled down). Continuous downhill, no sags.
Silicone the spout into the valve inlet last. Scuff, bead, push, wipe, cure 24 h before water.
Screen the inlet, then test with a few gallons and watch the spout joint for drips.
PVC cement won't bond PETG. The spout joint is the only silicone joint in the whole build.
Plastic bulkheads & threads crack if cranked. Snug + ¼ turn, let the washers/gaskets seal.
The printed spout is ~¾" so it won't bottom out in the socket. Normal — silicone fills the gap.
Both hoses run continuously downhill. A sag traps air and the flow stalls.
Open standing water = mosquitoes. Mesh the inlet and any gap.
Zone 8a freezes rarely — open the diverter valve before a hard freeze so trapped water can't crack plastic.