How to check your gas bottle level: four practical methods
Four practical ways Australian and NZ households can check how much LPG is left in a gas bottle, from the warm-water trick to a smart level sensor.
Why it is hard to tell
LPG sits in the bottle as a liquid under pressure. The pressure stays roughly the same until the bottle is almost empty, so a simple pressure reading will not tell you whether you have half a bottle or a few days left.
That is why many people only find out the bottle is empty when the BBQ flame dies or the hot water goes cold.
1. The warm-water trick
Only if the supplier permits this method, use warm, never boiling, water and feel for a cooler area on the same side. Never heat a bottle to improve gas flow or use a flame. The metal feels cooler where the liquid LPG sits.
It is free and quick, but only gives a rough idea and has to be repeated every time.
2. Weigh the bottle
Australian gas bottles have a tare weight (marked TW) stamped on the collar. Before moving a portable bottle, turn off the appliance, close the bottle valve and disconnect according to the supplier’s instructions. Keep it upright, use scales rated for its full weight and subtract the tare in matching units, allowing for accessories not included in the tare. Do not lift a connected bottle or attempt to weigh a heavy installed cylinder yourself.
This is accurate, but awkward for heavy bottles and impractical for large 45 kg home bottles.
3. Stick-on and pressure gauges
Stick-on strips change colour with temperature, so they work on a similar idea to the warm-water trick. Inline pressure gauges do not reliably show how much LPG remains or provide a dependable near-empty warning, because pressure depends on temperature and gas composition.
4. A smart level sensor
A magnetic level sensor such as the WiseTank Bluetooth or WiFi model attaches under the centre of a steel gas bottle and measures the liquid level from below. The TANK IOT app shows the remaining percentage and can alert you when the level gets low.
It works with steel bottles that have a flat area in the centre of the base. It does not work with aluminium or composite bottles because the magnet cannot hold on.
Which method should you use?
For an occasional BBQ bottle, the warm-water trick or scales are fine. For a home bottle that runs your hot water or cooking, or a caravan bottle on a long trip, a sensor saves you checking by hand.