| Gigaliters (GL) | Kiloliters (kL) |
|---|---|
| 1 Gigaliter | 1000000 kL |
| 2 Gigaliters | 2000000 kL |
| 3 Gigaliters | 3000000 kL |
| 4 Gigaliters | 4000000 kL |
| 5 Gigaliters | 5000000 kL |
| 10 Gigaliters | 10000000 kL |
| 20 Gigaliters | 20000000 kL |
| 25 Gigaliters | 25000000 kL |
| 50 Gigaliters | 50000000 kL |
| 100 Gigaliters | 100000000 kL |
| Reference | Gigaliters (GL) | Kiloliters (kL) |
|---|---|---|
| A teaspoon | 5 × 10-12 GL | 0.000005 kL |
| A can of soft drink | 3.3 × 10-10 GL | 0.00033 kL |
| A wine bottle | 7.5 × 10-10 GL | 0.00075 kL |
| A bathtub | 0.00000015 GL | 0.15 kL |
| An Olympic swimming pool | 0.0025 GL | 2500 kL |
The gigalitre is a unit of volume equal to a billion litres, or one million cubic metres. Its symbol is GL. It is also exactly one cubic hectometre, which is the same quantity written in coherent SI form. It is the unit in which reservoirs, catchments and national water plans are counted, and it is where water measurement stops describing supply and starts describing landscape.
Dam storage is its principal use. Australian reservoir levels are published in gigalitres and as a percentage of a stated capacity in the same unit, so a city's water security can be read as a single number that changes week by week. Warragamba Dam, which supplies most of Sydney, holds a little over two thousand gigalitres when full, and the whole system a few hundred more.
Policy is written in it as well. The Murray-Darling Basin Plan set out to recover water for the environment in gigalitres, and every argument about that plan has been an argument about how many gigalitres should come out of irrigation and go back into rivers. Desalination plants are rated the same way: a large plant produces something like ninety gigalitres a year, which is a meaningful fraction of a city's demand.
Australians have an informal comparison for it. The volume of Sydney Harbour is taken as roughly five hundred gigalitres, and flood volumes, storage losses and river flows are described in harbours as casually as elsewhere they are described in swimming pools. Two thousand Olympic pools make one gigalitre, which is the more portable comparison for readers elsewhere.
The unit's identity with the cubic hectometre is worth holding on to. Spanish and Latin American hydrology publishes reservoir capacity in cubic hectometres, so a Spanish figure of 500 hm³ and an Australian figure of 500 GL describe exactly the same body of water, and any comparison between the two systems needs no arithmetic at all.
Above the gigalitre, water quantities pass to the cubic kilometre, which is a thousand of them, and are used for lakes, ice sheets and global budgets rather than for anything a government can manage. Below it, the megalitre takes over for individual farms, works and pipelines.
One gigalitre equals 1,000,000,000 litres, 1,000,000 cubic metres, 1 cubic hectometre, or about 264 million US gallons.
The kilolitre is a unit of volume equal to one thousand litres, and therefore exactly one cubic metre. Its symbol is kL. The two names describe the same quantity, and which one appears depends entirely on the trade and the country: water utilities in the southern hemisphere say kilolitre where European ones say cubic metre.
Household water is where most people meet it. Australian, New Zealand and South African water bills are issued in kilolitres, tariffs are set as a price per kilolitre with rising blocks for heavier use, and drought restrictions are expressed as an allowance of so many kilolitres per household per quarter. A typical family uses between fifty and two hundred a year, so the annual bill fits in three digits.
Because the unit equals a cubic metre, it also carries an unusually direct physical meaning. A kilolitre of water weighs one tonne and would fill a cube one metre on each side, so a household allowance of a hundred kilolitres is a hundred tonnes of water, delivered, pumped and treated. Stating it that way is one reason the unit appears in conservation campaigns as often as on invoices.
Bulk liquid logistics uses it for cargo. A flexible tank fitted inside a shipping container carries around twenty-four kilolitres of wine, juice or edible oil, road tankers are rated in kilolitres, and depot storage is planned in thousands of them. Japanese petroleum statistics are published in kilolitres rather than in barrels, which makes Japanese energy figures awkward to compare with those of countries that use the barrel.
Industry generally prefers the cubic metre for the same quantity, because it is the coherent SI form and because it multiplies cleanly with metres of head, square metres of surface and other dimensional quantities. The kilolitre survives where the substance being measured is a liquid sold to the public, which is exactly where a name containing the word litre reads more naturally.
Converting is trivial in one direction and awkward in the other. One kilolitre is one cubic metre exactly and a thousand litres exactly, but 264.2 United States gallons and 220 imperial gallons, and about 6.29 barrels of oil, none of which are round numbers.
One kilolitre equals 1000 litres, 1 cubic metre, about 264.2 US gallons, or about 220 imperial gallons.