How much rain a Kasese roof could catch in a typical year, how many jerrycans of bought water that stands in for, and how long it would last a household when the taps go dry. An estimate — and never drinking water untreated.
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From Town Tools. For the current version, visit https://www.towntools.org/kasese-kasese-ug/catching-the-rain
When Kasese's taps fail, water gets expensive fast. In the crisis that hit Central and Nyamwamba divisions, the hardest-hit areas were Kizungu, Kanyangeya and Nyakasanga West: residents trekked for water, fetched from streams and roadside drainage channels, and some drew contaminated water from the Nyamwamba itself, while tap operators put a jerrycan up from UGX 100 to between UGX 300 and UGX 500 (The Independent, January 2025; Daily Monitor). The piped supply is pumped down from Kilembe — the same valley the river tears through most years.
Rain is the one water that arrives on its own: about 864 mm of it in a normal year, in two seasons, landing on the mabati roofs of the whole town. This page works out what your roof could catch in a typical year, which months would fill a tank, how many days of household water that is, and how many jerrycans of bought water it stands in for.
"Are the Taps Dry?" tells you whether the water is off in your area right now. This page is about what a household can do between the cuts.
In a typical year, this roof could catch about
34,500 litres of water
from about 864 mm of rain a year
Days of household water
~276 days
for 5 people at 25 L a day
Bought water it replaces (jerrycan)
≈ 1,727.4 a year
one 20 L load ≈ USh 100
Wettest month
6,000 L
the most a tank would bank at once
When the tank fills
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.
JanJan: 472 L
FebFeb: 584 L
MarMar: 2,100 L
AprApr: 3,300 L
MayMay: 3,000 L
JunJun: 964 L
JulJul: 1,300 L
AugAug: 4,100 L
SeptSept: 5,700 L
OctOct: 6,000 L
NovNov: 4,300 L
DecDec: 2,600 L
And right now
About 80 mm of rain has fallen in the last 30 days — enough for this roof to have caught roughly 3,200 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.
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
Rain off a roof is not drinking water. It washes dust, soot, bird droppings and leaf litter off the mabati, and the first rain after a dry spell carries the worst of it down. Divert the first few minutes of every storm away from the tank, keep the tank covered and screened against mosquitoes, and boil or properly treat anything anyone is going to drink. This matters more here than in most places: when the taps failed, residents were reported drinking from roadside drainage channels and from the Nyamwamba itself. Stored rain is a better starting point than either — but only once it is treated. For washing, cleaning and the toilet it is fine as it comes.
Rainfall varies a lot around here
These are typical-year figures for the town, not a measurement of your roof and not a promise about this year. Three things are worth knowing before you size a tank. First, they come from a weather model, not from a rain gauge in Kasese: monthly medians of the complete years 2017–2024 from the ECMWF reanalysis, read at the model's cell for the town, at about 984 m. In that same record the yearly totals ran from 642 mm in the leanest year to 1,119 mm in the wettest, so a thin year gives noticeably less than the table above. Second, these numbers describe the town, not the mountains: the Rwenzori slopes above Kilembe get far more rain than the valley floor does — which is why the river can flood on a day when it is dry in town — and rainfall varies sharply from one part of this valley to the next. Third, the models disagree here. The coarser ERA5 reanalysis, which averages the 5,000-metre massif into the valley, returns about 3,850 mm a year for this same point, more than four times the roughly 900 mm the town's own climate record gives. We use the lower, town-scale figures deliberately, because over-estimating what a roof will catch is the mistake that leaves a tank empty.
What goes into the numbers
Why not every drop is caught
Assumes a hard roof — the mabati iron sheets most houses here are roofed with, or tile or concrete — with gutters in reasonable order. About a fifth of the rain that lands is lost: splash, gutters overflowing in a heavy downpour, and the first dirty wash you throw away at the start of a storm. A thatched roof, or one with broken or missing gutters, catches a good deal less.
How much water a person uses
Counted at 25 litres per person per day — drinking, cooking, washing and the toilet. The widely quoted WHO background paper on domestic water puts the minimum for basic health protection at about 20 litres a person a day, of which 7.5 litres is drinking and cooking; the Sphere standard for emergencies is 15. We count 25 on purpose: assuming people use more is the safer way to be wrong about how long a tank lasts. If your household gets by on less — many here do, especially when the taps are off — the water will stretch further than the days shown.
jerrycan
A 20-litre jerrycan from a tap operator normally goes for about UGX 100. The trouble is that the price moves exactly when the supply fails: in the water crisis that hit Kizungu, Kanyangeya and Nyakasanga West, operators put the same jerrycan up to between UGX 300 and UGX 500, and families who could not pay went to open sources instead (The Independent, January 2025). Prices vary by area and by how far the water has been carried — treat this as a rough guide, not a rate.
Worth knowing
Two rainy seasons, and a long thin gap
The rain comes twice: March to May, then a bigger run from August into November. October is the wettest month in these figures at about 150 mm, with September and November close behind. January and February between them barely make 27 mm. A tank sized only to catch one heavy downpour will overflow in October and stand empty in February — what matters is not how much falls in the wet months but how much you can still be holding in the dry ones.
Why the taps fail in the first place
Kasese's piped water is pumped from Kilembe, up the Nyamwamba valley — the same valley the river tears through most years. The council puts projected coverage at about 75.7%, but dry spells keep returning to Kizungu, Kanyangeya and Nyakasanga West. In January 2025 the NWSC branch manager said the corporation was finalising infrastructure to draw water from the River Kyanzutsu to the main treatment plant. A roof tank does not fix the supply; it means a cut costs you a walk instead of UGX 300 to 500 a jerrycan.
First flush, in one sentence
Fit a diverter — a length of downpipe that fills up and closes itself off before the clean water reaches the tank — so the dirtiest water from the start of each storm never gets in. It is the cheapest single thing you can do to improve what comes out of the tap.
Is the water off right now?
This page is about the rain you can store between cuts. For whether the taps are actually dry in your area today — reported by neighbours, with the NWSC toll-free line to report a burst or a shut-off — see the other water page. Are the Taps Dry?.
Where to get help
National Water & Sewerage Corporation (NWSC)NWSC pipes Kasese's water from Kilembe. The toll-free line 0800 200 977 runs 24 hours — use it to report a burst, a leak or no water at all.
Kasese Municipal CouncilThe council on +256 787 885452, and your division office — Central, Nyamwamba or Bulembia — are where to ask about water schemes and drainage in your area.