Pressure Pump or Gravity Feed: Which Suits Your Tank?

Water stored above where you use it flows by gravity, with no power. The question is whether it gives enough pressure.

1. Height gives pressure

Every 10 metres of height (head) gives about 98 kPa, close to 1 bar or about 14 psi. A tank on a 2 m stand gives only about 20 kPa at a tap at ground level, which is a gentle trickle through a hose.

2. When gravity works well

• Stock troughs and garden drippers that need little pressure.
• Tanks on a hill well above the house.
• Backup supply when the power is off.

3. When you need a pump

• Showers, washing machines and hot water systems usually need much more pressure.
• Long or uphill pipe runs.
• Sprinklers.

4. Mixing both

Many places use gravity for troughs and a pressure pump for the house. Some pumps have a bypass that lets gravity water through when the power's out.

5. Quick summary

• 10 m of height ≈ 98 kPa.
• Gravity suits troughs and drippers.
• Houses usually need a pump.
• Try the Water Pressure From Height Calculator.

General information only. Check the maker's instructions, and ask your council about approvals.

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