Type your roof size to see how much rain it could catch here — in a typical year and over the last 30 days — and how many days of household water that is.
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From Town Tools. For the current version, visit https://www.towntools.org/luganville-sanma-vu/rainwater-harvesting
Litres this roof catches each month of a typical year. The rains do the work in a few months — storage carries you through the dry ones. The rains here come November–April.
JanJan: 11,500 L
FebFeb: 12,100 L
MarMar: 10,400 L
AprApr: 10,400 L
MayMay: 6,800 L
JunJun: 6,600 L
JulJul: 3,700 L
AugAug: 3,500 L
SeptSept: 4,000 L
OctOct: 5,900 L
NovNov: 7,200 L
DecDec: 8,100 L
And right now
About 201 mm of rain has fallen in the last 30 days — enough for this roof to have caught roughly 8,000 litres.
These are estimates, not a promise
The catch is plain arithmetic from your roof size and average rainfall — real water depends on your roof, gutters, the first wash thrown off a dusty roof, and how big a tank you have to hold it. Treat it as a starting point for sizing a tank, not a guarantee.
Fewer than six in ten households in greater Luganville are on the piped supply, so for most of the rest the roof is the water system. Even on the pipes it is not dependable: the town's pumps run on electricity, cuts arrive with little or no notice, and after the earthquake of 30 March 2026 Red Corner, Maritime College, the Radio Station area and St Michel went two weeks with no tap water. A tank changes what a dry spell or a broken main costs a household. Put your own roof size in below and every figure follows it. Nothing you type leaves this page.
Live rainfall from Open-Meteo (CC BY 4.0) — a weather-model estimate for the area, not a rain gauge on your street. Updated .
Rain off a roof is not drinking water
Treat it before anyone drinks it. A roof collects dust, bird and rat droppings, leaves and rust between showers, and all of that washes into the tank with the rain. Bring the water to a rolling boil, or filter and disinfect it, before it is used for drinking, cooking, washing food or cleaning teeth. Santo has had reason to be careful this year: the Ministry of Health declared a watery-diarrhoea outbreak with more than a hundred cases between late August and September 2026. Untreated tank water is fine for washing, flushing and the garden.
Rainfall varies a lot around here
These monthly figures are a long-run average, and a real year here is rarely close to it. In NOAA's monthly record for the Pekoa airport station just east of town, Februaries between 1991 and 2020 ran from 89 mm to 756 mm, and the driest August in that record brought 26 mm against the 87 mm average used above. Rain is local as well as uneven — a tropical downpour can soak one end of town and miss the other. So size a tank for a poor year rather than an average one.
What goes into the numbers
Why not every drop is caught
The sums assume 8 of every 10 litres that land on the roof reach the tank. That is about right for the corrugated iron roofs most houses in town have, with gutters in good order. Thatch holds the rain rather than shedding it and catches far less, and a side of the roof with no gutter under it catches nothing at all.
How much water a person uses
The days-of-water figure counts 50 litres a person a day. That is the level the World Health Organization calls intermediate access, where drinking, cooking and washing are all covered. A household living off a tank usually gets by on much less: at 20 litres a person a day, which WHO treats as basic access, the same water lasts two and a half times as long.
Worth knowing
The dry months are what the tank is for
July, August and September together bring less rain than February alone. So the limit on a household here is storage rather than rainfall: a roof can take in most of its year's water between November and April and still leave the house short in September, because by then what matters is only what the tank still holds. Work out what your house gets through in those three dry months and make the tank at least that big. Whatever more the roof catches in February runs out of the overflow.
Throw the first rain away
The first few minutes of rain carry whatever is sitting on the roof straight into the tank. A first-flush diverter — at its simplest a capped length of downpipe you empty by hand — sends that first wash to the ground instead. It is the cheapest change you can make to a system, and it matters most after a long dry spell, when the roof has had months to collect.
Keep the tank closed — mosquitoes breed in it
Dengue reached Santo in late September 2026, with cases in the Luganville and East Santo area councils, and the mosquito that carries it lays its eggs in standing water. A tight lid, with fine mesh over the inlet and the overflow, keeps the mosquitoes and the leaves out together. Open drums and buckets left standing in the yard are the ones to deal with first. Daily Post: dengue spreads to Santo.
Strap the tank down for cyclone season
Cyclone season runs November to April and peaks January to March — the same months that fill the tank. Cyclone Harold damaged 50 to 70 per cent of Luganville's buildings in April 2020. An empty tank is light enough for a storm to carry off, so fix it to its base and check the gutter brackets, and plan on flushing and cleaning the tank afterwards, when everything loose has been through the air. VMGD warnings and forecasts.
The tap is not the clean option either
None of this means rain needs more care than the mains do. The Department of Water Resources' own environmental assessment for the ADB-funded rebuild, written in June 2024, records that Luganville's chlorination has been out of service since 2021 and that the piped water regularly fails drinking-water standards. Whichever supply it came from, water for drinking and cooking is worth boiling or treating.
Where to get help
Department of Water ResourcesThe department that runs Luganville’s piped supply and builds rainwater-harvesting systems around the country. Its own lines are +678 22423 and +678 33435, Monday to Friday 8:00 to 17:00, answered at its head office in Port Vila. A separate Department of Urban Water Services, approved in 2025, is due to take over service in Luganville and Port Vila. The department’s homepage does not open — this link goes to the page that does.