How full are southern Africa's city dams?
How full are the reservoirs that supply Harare, Bulawayo, Gaborone, Windhoek, Lilongwe, Maputo, Cape Town, Durban and Maseru, how low have they gone since 2017 and how often, and has storage kept up with the cities' growth?
12 November 2026 · Water, Real estate · Read the article on dotzedw.com
Utilities publish reservoir levels when they choose to, in different formats, and often only in a crisis. We measured 23 reservoirs behind nine SADC cities on every clear satellite pass since January 2017, more than 9,000 measurements, and set them against how much each city has built.
This page holds each city's reservoirs month by month, the lowest and latest readings, how often each city was below half, every reservoir on its own, and building growth from the city models.
What members get
- Each city's supply reservoirs together, month by month since 2017, against the fullest they have been
- The lowest month and the latest for every city and every reservoir
- How often each city's reservoirs were below half, and median fill by year
- Building growth 2016 to 2023 for the cities with a city model, and downloads
This study is part of the Individual plan
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How we did it
Each reservoir's outline from OpenStreetMap, plus a margin. On every Sentinel-2 image since January 2017, the clear pixels inside it and the clear pixels that were water (a water index, or the image's own water class); passes with at least 90% of the reservoir clear, isolated readings far from their neighbours dropped, and a monthly median.
Each reservoir and each city is compared with the fullest it has been since 2017 (the 95th percentile of its months), not with its design capacity. Surface area falls more slowly than stored volume.
Building growth from the dotzedw city models (Google Open Buildings 2.5D Temporal). Contains modified Copernicus Sentinel data 2017 to 2026.
What this cannot tell you
- Area, not volume; fullest since 2017, not design capacity.
- Surface reservoirs only: boreholes, recycled water and transfer pipelines are not counted.
- The Vaal Dam (Gauteng), Mtshabezi (Bulawayo) and Bokaa (Gaborone) are not included.
- Lilongwe's Kamuzu Dam I was raised in 2023; before then its fill compares the old reservoir with the new one.