Off-Grid Rain Catch Upgrade – 5 Tiny Houses, 1 Pump House

Long-time lurker, first-time poster. Huge thanks to this community – your past advice has been invaluable.

The Situation:
Our off-grid property runs on rain catchment with a small pump house and filtration system that's worked perfectly for 8 years. We're now adding 5 tiny houses (composting toilets + ultra-low-flow fixtures) and need to upgrade.

The Plan:
Originally considered a second uphill pump house, but expanding the existing one is much easier. I've already bought some components but am open to swapping if needed.

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What I Need Help With:

1. Pressure Tank

· AI suggested: Amtrol Well-X-Trol WX-255 (81 gal)
· Thoughts?

2. Pump

· Need constant 50 PSI @ 15–20 GPM for 5 tiny houses
· AI recommended: Grundfos SQE (VFD) or Grundfos Scala2 (floor mount)
· Which is better for my setup?

3. Filtration

· I currently have a Pelican/Pentair PUV-7 (7–16 GPM). Can I keep it?
· AI suggested adding:
 · 50-micron pre-pump sediment filter
 · 5-micron fine sediment filter
 · 5-micron carbon filter
 · 20 GPM UV (after carbon)
· Will my PUV-7 work as the UV stage, or do I need a higher-flow unit?

4. Transfer from Downhill Tanks

· Main tank is uphill; larger storage tanks are downhill.
· Plan: Use a float switch + small solar pump near downhill tanks to top off the main tank.
· Should I use a submersible or external pump? Brand/model recommendations?

5. I am a novice!  Any missing parts or regulators that would make this more efficient?
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Photos attached: pump house, water tank, property map with expansion layout.

Thanks in advance for any guidance!

PICTURES
1. Property water map/plan
2. Main Pump-house and 2500g tank
3. 4. & 5 Uphill tank and pump assembly. Never used this… (Good parts if needed)
6. Inside mail pumphouse - working well for 8 years
7. Utility hub 1 of 5