Cape Water

WESTERN CAPE WATER SUPPLY

Cape Town

75.5%

of our dams’ combined capacity

City reading · 2 October 2026

Checking the latest official reading…

678.0 billion litres stored6 major dams
◷ WEEKLY COMPARISON

Combined storage

Weekly report · 28 September 2026

−0.5 pts

15.8 percentage points below the same week last year.

RAINFALL OUTLOOK
—mm

Forecast across the dam catchments

Loading forecast…

Dam levels

Percentage full · 2 October 2026 · Select a dam for more detail

How much each dam holds

Latest City reading · billion litres

All six dams, on the same scale.

Stored waterFull capacity

Individual volumes are estimated from the City’s rounded percentages. Outlined bars show full capacity; filled bars show stored water.

Historical storage outlook

Past patterns · not a forecast

The latest dam reading, followed by the range of storage changes seen in past seasons.

Median storageHistorical range

Loading historical observations…

—lowest point of the median

What does the 10% line mean?

At very low levels, water becomes harder to extract from dams. The dashed line marks a historical 10% reference from the City’s 2019 Water Strategy. It does not mean that exactly 90% of the water is usable, or that taps stop when storage reaches 10%.

Use it as context for low storage, not a countdown to water restrictions. Actual supply depends on individual dams, water quality and how the system is operated.

City Water Strategy · endnote 1
Monthly values and method

Every complete, calendar-matched 12-month season is replayed from the current reading using its recorded net storage changes. At each month, the line shows the median across those replays, and the shaded area shows their lowest and highest values. The median is a summary, not one actual historical season.

Storage changes already include rainfall, demand, evaporation, transfers and operating decisions. We do not rank the paths by rainfall or treat wetter years as automatically safer. The first month is prorated for days remaining, monthly storage is capped at 100% with excess discarded, and depleted paths remain at zero for the remaining horizon.

This is a comparison with past conditions, not a rainfall forecast or calibrated risk estimate. It does not adjust for current demand, climate trends or new water sources. Historical observations: UCT CSAG Big Six Monitor, January 2008–May 2020.

MonthLowestMedianHighest

Water-saving advice from the City of Cape Town.

Sources and updates

Cape Water is an independent dashboard, not a City of Cape Town service.

Dam levels

The latest and weekly readings come directly from the City of Cape Town’s published tables. We use the City’s combined percentage and storage volume; individual dams are not averaged equally.

Comparisons

Weekly changes compare the same weekly series. The headline may be newer, so it is kept separate. “Points” means percentage points: 76.6% to 76.1% is a fall of 0.5 points. Levels above 100% can occur when dams spill.

Storage volumes and low-storage reference

Individual stored volumes are calculated from each dam’s full capacity and rounded level. The combined volume comes directly from the City. The 10% reference follows the City’s 2019 Water Strategy; it marks a level where extraction becomes progressively more difficult, not a precise usable-water limit or a trigger for supply interruptions.

Rainfall

Catchment forecasts originate with Open-Meteo and are supplied by the Cape Town Dam Levels open data feed (CC0). The chart shows the feed’s dated forecast window; rainfall is a forecast, not a measured addition to storage.

Freshness & availability

The page checks for new readings when opened and every 30 minutes while visible. If a source is unavailable, the last saved snapshot stays on screen with its original date and a notice. Reports older than nine days are marked as older readings. Forecasts past their end date are marked as expired.

Privacy

No accounts, advertising trackers or tracking cookies. We count page views with a new random reference for each page load; we do not store your IP address, a visitor identity or browsing history in the counter. Repeat visits count again. The month follows South African time. Your browser also stores a copy of the latest successful dam readings. Netlify hosts the site and processes ordinary web requests, including IP addresses for security and rate limiting.

About the storage outlook

Where the data comes from

The starting level is the latest published City of Cape Town reading. Monthly historical storage comes from UCT’s Climate System Analysis Group, compiled from City, DWS and Aurecon records.

How often it updates

The site checks City readings when opened and every 30 minutes while visible, plus whenever you press Refresh readings. The City publishes on its own schedule; these are not real-time measurements. A new reading recalculates the outlook automatically.

The historical reference covers January 2008–May 2020. It is a fixed dataset, retrieved on 3 October 2026; it does not update every 30 minutes. The chart uses all complete seasons that match the starting calendar month.

What the range means

The lower edge, middle line and upper edge are the minimum, median and maximum across historical replays at each month. They are ordered by storage, not rainfall, and always stay in that order. The range is not a confidence interval and the median is not a prediction.

What affects storage

These historical changes include rainfall, water demand, evaporation, transfers and operating decisions. Total rainfall alone cannot explain how low storage may fall: when the rain arrives also matters.