16/01/2026
This is explains an indirect water supply system that uses a cistern tank (ground tank) + pump + elevated tank (roof tank) to deliver stable water pressure to a house/building.
How the system works (step-by-step)
1. Public water supply → Cistern tank (bottom tank)
- City water enters the cistern tank through a float valve (like a toilet float).
- When the cistern water level is low, the float opens and refills.
- When the cistern is full, the float closes to stop water and prevent overflow.
2. Cistern tank → Pump suction line
- A foot valve at the bottom of the suction pipe keeps water inside the pipe (prevents losing prime).
- This helps the pump start smoothly without sucking air.
From Plumbing home
3. Pump pushes water up to the Elevated tank (top tank)
- The pump sends water through the discharge line (shown going upward).
- Along the line you see key fittings:
- Gate valve: lets you shut off water for maintenance.
- Check valve: prevents water from flowing backward (so the elevated tank doesn’t drain back through the pump).
- Pressure gauge: shows pump discharge pressure.
- Universal joints: reduce vibration and stress on piping.
4. Automatic level control in the Elevated tank
- The elevated tank has level sensors:
- LOW LEVEL ON: when water drops to this point, the pump is allowed to run/refill.
- HIGH LEVEL OFF: when water reaches this point, the pump stops.
- There is also an overflow line to safely discharge extra water if something fails.
5. Water supply to the building
- Water exits from the elevated tank outlet and feeds your house by gravity.
- This gives steady pressure, even if city pressure is weak or cuts out.
6. Extra protection shown on the right side
- The blue tank on the right (often used as a pressure/expansion tank) helps reduce pressure spikes (water hammer) and stabilizes the system.
Why people use this setup
✅ Works well when city pressure is weak or inconsistent
✅ Gives more stable water pressure for showers, taps, and toilets
✅ Keeps a backup water reserve during supply interruptions
✅ Protects the pump and piping with check valves and level automation
Quick maintenance tips
- Clean the cistern/elevated tank regularly (sludge & algae control).
- Check float valves and level sensors to avoid overflow or dry-running.
- Inspect check valve and foot valve if the pump loses prime.
