How Long Does a 45kg Gas Bottle Last? Christchurch Guide

Quick answer

For a family of four using LPG for cooking and hot water, one LPG supplier's New Zealand guide estimates a 45kg bottle lasts about 2 to 3 months, and more than 5 months for a couple. Hot water uses most of the gas, so long showers shorten it. Gas heating shortens it further, and every bottle runs down faster in a Christchurch winter.

In Christchurch, gas at home means LPG. Most homes that cook or heat water with gas use 45kg bottles or a bulk tank, and some streets have piped LPG. Because you pay for every bottle, it helps to know what actually empties one.

This guide uses published supplier estimates to show how long a bottle lasts for hot water, cooking and heating, why winter changes the numbers, how two-bottle changeover setups work and where bottles can be installed.

How long does a 45kg gas bottle last for hot water?

Hot water is the biggest user of LPG in most homes, and a 45kg bottle running a typical continuous flow unit lasts anywhere from about three weeks to over three months, depending on how long the hot taps run. A full 45kg bottle holds about 2,200 MJ of energy, and a continuous flow water heater can burn well over 100 MJ an hour at full output.

The table below uses one supplier's published New Zealand estimates. They assume the heater runs at its maximum rate the whole time, so real homes on lower settings will see longer figures. Count every minute of hot water use, not just showers.

Hot water use per day	16 L/min unit	26 L/min unit
10 minutes	About 105 days	About 66 days
20 minutes	About 52 days	About 33 days
30 minutes	About 35 days	About 22 days

How long does it last for cooking only?

For cooking alone, a 45kg bottle lasts many months and often more than a year. The same supplier estimates that a 9 MJ cooktop burner used for an hour a day would empty a bottle in about 244 days, and used for 30 minutes a day it would last about 489 days.

Most households use two or three burners for shorter periods rather than one burner for an hour, so the realistic figure sits somewhere in that range. Homes that only cook on gas often find a single bottle, or a smaller bottle, does the job. If you are planning a new cooktop, a gas fitter can size the supply and the regulator for the appliance.

Why does my gas run out faster in winter?

Gas runs out faster in winter because the water coming into the house is colder, so the heater burns more gas to bring it up to temperature, and gas heaters are running as well. Christchurch averages about 80 ground frost days a year, and a cold inlet supply on frosty mornings adds up over a season.

Heating is the big swing factor. The supplier's estimates suggest a 15 MJ gas heater run for three hours a day would empty a 45kg bottle in about 49 days, and a 25 MJ gas fire run for two hours a day in about 44 days. Add that to hot water and cooking and a single bottle can disappear within weeks in July.

If your gas use has jumped and the weather does not explain it, consider a leak. A faint smell near the bottles, the meter or an appliance is the first sign, and it needs gas leak repairs rather than a refill.

Bottles in the wrong place or running out too fast?

Cheeky's Plumbers checks your LPG setup for leaks, moves bottles, fits changeover regulators and services gas water heaters, with the price agreed first.

0800 758 622 Book Online Get a quote

Should I have two bottles with an automatic changeover?

Yes, for any home that relies on LPG for hot water. Most homes on bottled LPG have two 45kg bottles connected through an automatic changeover regulator. When the bottle in service runs empty, the regulator switches to the full one without interrupting the supply, and an indicator on the regulator shows the change.

That gives you the time of one full bottle to arrange a swap. The habit that works is simple:

Check the changeover indicator whenever you pass the bottles
Order a replacement as soon as the indicator shows the reserve bottle is in use
Do not open the regulator or swap hoses yourself; leave connections to the delivery driver or a gas fitter
If the hot water fails while a full bottle is connected, the fault is likely the regulator or the appliance

Where can 45kg bottles go on my property?

45kg bottles go outside, upright, on a firm level base, and clear of openings into the house and below-ground spaces. WorkSafe says LPG cylinders should be stored upright, because lying one down brings liquid into contact with the safety valve and stops it working correctly.

LPG is heavier than air, so it settles in low spots if it leaks. The installation standard AS/NZS 1596 sets clearances from doors, windows, vents, drains and ignition sources, and those distances vary with the layout. Your gas fitter checks them when installing or moving bottles, along with access for the delivery driver and a sound way of securing the bottles to the wall.

Our gas fitting team can move bottles to a better spot, fit a new changeover regulator or run a supply to a new appliance.

Bottles, bulk tank or piped LPG: what suits a Christchurch home?

Bottles suit most homes, a bulk tank suits heavy users, and piped LPG is only an option on the streets where it already runs. Christchurch once had a coal gas network from the Christchurch Gasworks, which began in 1864 and reached all but the outer suburbs until it closed in the early 1980s. Today LPG arrives at Woolston by pipeline from Lyttelton Port, and some streets are on piped LPG while most gas homes use bottles or a tank.

A bulk tank is refilled on site by a tanker, so there are no bottles to swap, but it needs its own approved position and clear access for the truck, which rules it out on some smaller sections. Before you change supply, look at the appliance as well. An older storage water heater can waste gas, and a modern continuous flow unit only burns gas while a tap is running. Our pages on gas hot water and continuous flow hot water compare the two.

When should you call a gas fitter?

Call a gas fitter for any work on the bottles, regulator, pipework or appliances, and call straight away if you smell gas. WorkSafe advises using an authorised gas fitter for gas work, who should give you the certification paperwork for the job.

Cheeky's Plumbers has gas fitters across the city and the surrounding towns, where many newer homes in places like Rolleston and Halswell cook and heat water with LPG. See our gas fitter Rolleston and gas fitter Halswell pages, or book online for bottle relocations and new appliances.

Frequently Asked Questions

How can I tell how much gas is left in a 45kg bottle?

The changeover indicator tells you which bottle is in use, not how full it is. The practical approach is two bottles and a prompt reorder when the indicator changes, so the bottle in service is never your last one.

Is a 9kg bottle enough for a cooktop?

A 9kg bottle can run a cooktop that is used lightly, but it empties about five times faster than a 45kg bottle and needs swapping by hand. For daily cooking, most households find 45kg bottles, connected outside by a gas fitter, more practical.

Can I install 45kg bottles inside a garage?

No. 45kg bottles are installed outside in the open air, where any leak can disperse rather than build up in an enclosed space. A gas fitter can find a compliant outdoor position and run the pipework to the appliances inside.

Does a continuous flow unit use gas when no tap is running?

No. It only burns gas while hot water is flowing. Many outdoor units use a little electricity for frost protection in cold weather, which is worth knowing in Christchurch, but that does not empty the bottle.

What should I do if I smell gas near the bottles?

Turn off the bottles at the valves if you can do so safely, avoid switches and flames, and move away from the area. Then call a gas fitter. Do not try to tighten fittings or test for leaks with a flame.