Taiwan's reservoirs are in comfortable shape in mid-July 2026 — a quiet contrast to the island's 2021 water emergency. The three reservoirs that supply Taiwan's biggest cities are all well-stocked: Zengwen, the largest in the country and the backbone of Tainan and Chiayi in the south, sits near 77% of its effective capacity; Feitsui, which supplies Taipei, is around 80%; and Shimen, serving Taoyuan and Hsinchu, is essentially full. The one striking outlier is the small Agongdian Reservoir near Kaohsiung, at under 5%. All of this is measured by Taiwan's Water Resources Agency (WRA), whose daily open data makes the island one of the most transparent water reporters in the world — the exact opposite of a country that has just gone dark on its reservoir data. The live map is on the Taiwan reservoir levels page.
Key takeaways
- Taiwan's major city-supply reservoirs are healthy in mid-July 2026. Zengwen (
77%), Feitsui (80%, Taipei) and Shimen (100%, Taoyuan/Hsinchu) are all well-filled, as are Nanhua (98%) and Sun Moon Lake (~98%).
- The one outlier is Agongdian near Kaohsiung, under 5% full — but it is a small, off-channel reservoir, not a primary supply source, so its low level is not a city-supply alarm.
- Taiwan is a world-class open-data reporter. The WRA publishes daily, machine-readable reservoir data, earning Taiwan 4th of 167 countries on the 2026 Reservoir Transparency Index with a grade A.
- You will see two different-looking numbers, and both are right. Our Southern Taiwan region page reads about 45% full while Zengwen's own page reads ~77%. The gap is sedimentation: Taiwan's reservoirs have lost huge fractions of their original capacity to silt, so "% of effective capacity" (the WRA's figure) looks far healthier than "water stored ÷ original design capacity."
- The real risk in Taiwan is volatility, not today's level. The island depends on a handful of typhoons each year to refill; when they fail — as in 2020–21 — it can go from full to rationing in a single dry season.
The open-data contrast
It is worth stating plainly, because it is unusual: Taiwan is one of the best places in the world to watch reservoir levels in real time. The Water Resources Agency (WRA), part of the Ministry of Economic Affairs, publishes daily reservoir readings — storage, percentage full, inflow and release — through an open data platform and a disaster-prevention information service, with a genuine API rather than a scraped web page.
That openness puts Taiwan 4th out of the 167 countries assessed in the 2026 Reservoir Transparency Index, with an overall score of 86.6 (grade A, "Excellent") and one of the highest technical-accessibility marks in the entire index (88/100). It is the mirror image of the situation in South Africa, where the national bulletin has stopped updating and there is no API to fall back on. When a source publishes daily and openly, a drought shows up immediately and publicly; when it does not, the public is left guessing. Taiwan is firmly in the first camp.
Where levels stand now
As of the readings dated 16 July 2026, the picture by region — using each reservoir's official WRA fill against effective capacity — is broadly comfortable, strongest in the north:
- North — the healthiest. Shimen (Taoyuan/Hsinchu) is at capacity and Feitsui (Taipei) is around 80%. Taipei's supply is not a concern.
- Central — well-stocked. Techi (
92%), Sun Moon Lake (98%) and Liyutan (full) anchor the region; the small run-of-river Shihgang Dam is low by design, not by drought.
- South — mixed but adequate. The big supply reservoirs are fine — Zengwen (
77%) and Nanhua (98%) — while Wushantou (~61%) and the tiny Agongdian (<5%) pull the low end down.
There is no Day Zero risk anywhere in Taiwan today. The south, the region with the island's history of shortages, is carrying enough water in its major reservoirs to be out of the danger zone for this stage of the year.
The two-numbers puzzle: sedimentation
Here is a subtlety worth understanding, because it explains an apparent contradiction on this very site. Our Southern Taiwan region page shows the region around 45% full, yet the region's dominant reservoir, Zengwen, shows ~77% on its own page. Both numbers are correct — they measure against different denominators.
Taiwan's reservoirs are among the most heavily silted in the world. Steep mountains, erodible geology and typhoon-driven landslides wash enormous volumes of sediment into the dams, permanently shrinking the space available for water:
- Zengwen was designed to hold about 804 million m³; its usable capacity today is roughly 487 million m³ — nearly 40% lost to silt.
- Wushantou has lost close to half its original capacity.
- Nanhua (
48%) and Baihe (43%) have lost comparable shares.
The WRA — and the water managers who actually run the system — quote fill against effective (post-sedimentation) capacity, because that is the water that really exists: Zengwen at "77%" means 77% of what it can still hold. Our region rollups weight water against each reservoir's original design capacity, which is why a region can look emptier in aggregate than its healthy reservoirs suggest. The gap between the two numbers is, quite literally, the volume of silt. It is not a rounding error — it is Taiwan's slow-burning water problem in a single figure.
The real risk: typhoons, not today's level
Taiwan's water security is unusually binary. The island gets the bulk of its water from the plum rains of May–June and the typhoons of summer and autumn, and its shrunken reservoirs hold a smaller buffer than their headline capacities imply. That combination makes Taiwan prone to whiplash: a full year and a bone-dry one can sit back to back.
That is exactly what happened last time. In 2020, not a single typhoon made landfall on Taiwan — the first such year in over half a century — and by spring 2021 the island was in its worst drought in decades. Central Taiwan, including the tech-manufacturing hub around Taichung and Hsinchu, was placed on rationing (supply on five days, off two), farmland was fallowed to protect city and industrial supply, and southern reservoirs fell toward single digits. Sun Moon Lake, near full today, exposed a cracked lakebed. The crisis broke only when the rains finally returned.
Mid-2026 is the calm version of that story: the rains have come, the reservoirs are stocked, and the system is doing its job. The lesson from 2021 is that in Taiwan the number to watch is not the current percentage but the incoming weather — a quiet typhoon season is the thing that turns a comfortable July into a tense following spring. You can follow every reservoir's daily reading and trend on the Taiwan reservoir levels page.
The bottom line
As of mid-July 2026, Taiwan's reservoirs are healthy, its cities are well-supplied, and — unlike much of the world — you can verify all of that yourself from official daily data. The structural caveats are real: decades of sedimentation have quietly cut the island's usable storage, and its refill depends on a typhoon season that failed spectacularly in 2020. But those are risks to monitor, not a present shortage. For the wider view of which regions are actually near the edge, see our Day Zero watchlist for 2026, and compare how open each country's water data is in the Reservoir Transparency Index.
Frequently asked questions
Is Taiwan in a drought in July 2026?
No. As of mid-July 2026, Taiwan's major city-supply reservoirs are well-filled — Zengwen (77%), Feitsui (80%, Taipei) and Shimen (~100%, Taoyuan/Hsinchu) — after normal spring and early-summer rains. The only very low reservoir is the small Agongdian near Kaohsiung, which is not a primary supply source.
Why does southern Taiwan show around 45% when its main reservoir is 77% full?
Because the two figures use different baselines. The Water Resources Agency reports fill against each reservoir's effective (usable) capacity, while our regional rollup weighs stored water against original design capacity. Taiwan's reservoirs have lost large shares of their design capacity to sediment — Zengwen nearly 40% — so the aggregate looks lower than the WRA's per-reservoir percentages.
Could Taiwan have another water crisis like 2021?
Yes, structurally. Taiwan depends on plum rains and typhoons to refill reservoirs that hold less than their original capacity because of sedimentation. In 2020 no typhoon made landfall, triggering the worst drought in decades and water rationing across central Taiwan in 2021. A future dry typhoon season could do the same. The 2026 situation is comfortable, but the underlying volatility remains.
How reliable is Taiwan's reservoir data?
Very. Taiwan's WRA publishes daily, machine-readable reservoir data through an open platform, and Taiwan ranks 4th of 167 countries on the 2026 Reservoir Transparency Index with a grade A.
