3/4″ Poly Pipe Run: How Far Can You Go at 60 PSI?
(plumbing101.i234.me) — Running long stretches of 3/4″ SIDR polyflex pipe for garden irrigation can work well — as long as you plan for pressure loss, elevation, and flow rate. Here’s how to estimate what “reasonable” pressure looks like at the end of your line.
Question:
“I’m extending a 3/4″ SIDR polyflex line from my house for 300–500 feet with several hose bibs. The well pump delivers 60 PSI. The line rises 25 feet in elevation. Can I expect reasonable pressure at the far end if only one hose bib is open at a time?”
Answer:
Yes, it’s possible — but expect noticeable pressure loss, especially at 500 feet and 25 feet of elevation gain.
Here’s a breakdown of what’s happening:
- Starting pressure: 60 PSI at the well pump.
- Elevation loss: Every 2.31 feet of rise costs about 1 PSI, so 25 feet = ~11 PSI loss.
- Friction loss in pipe: At about 5 gallons per minute (a typical hose flow), 3/4″ SIDR polyflex loses roughly 4 PSI per 100 feet.
So, at 300 feet, that’s around 12 PSI friction loss + 11 PSI elevation = 23 PSI total loss.
Starting from 60 PSI, you’d end up with roughly 37 PSI at the final hose bib — still very usable.
At 500 feet, the loss climbs to around 20 PSI friction + 11 PSI elevation = 31 PSI total.
That gives you about 29 PSI at the far end — still workable for light garden use, but not ideal for sprinklers or pressure-sensitive irrigation.
Tips to Improve Performance:
- Use 1” polyflex for the first 200–300 feet, then reduce to 3/4”. This lowers friction dramatically.
- Install pressure regulators at each hose bib to prevent sudden surges when closing valves.
- Avoid unnecessary fittings or tight bends — each adds extra friction loss.
- Check well pump output: A booster pump or small inline booster can maintain stable pressure at long runs.
Bottom line: For a single-hose setup, you’re fine up to about 400 feet with usable pressure. At 500 feet, consider upsizing the first section or adding a pressure booster.
For a handy tool, try Engineering Toolbox’s pressure loss calculator to test your setup before you dig.
I’m Chris Mayer, writing for Plumbing 101.