How this record is made

Johannesburg Water (JW) posts pictures of its status boards on its website. This page says how we turn them into a record, how well we read them, what the record leaves out, and who makes it.

How we know

JW posts a board. Most days JW puts images of its System Update boards on its website. Each board lists reservoirs, towers and pump stations, each with a short status in JW's words and the time the board was printed.
We read every board. We have read 3,384 boards, with 38,957 rows, printed from 3 March 2025 to 29 September 2026. Each status keeps the time printed on the board and links to JW's own post and image.
We put JW's words on a scale. JW printed 1,514 different wordings. Each one goes on one of seven steps, from “supplying adequately” to “critically low”, one of them a warning that no water may occur. The words decide the step, not the colour.
We count days, and keep the gaps. A day's status is the worst JW reported that day. A day with no board stays a gap, never a normal day.
We join supplies to suburbs. JW's reservoir pages and supply table name the suburbs each reservoir or tower supplies. A suburb's page shows every supply JW names.

How well we read the boards

An AI model (Claude, made by Anthropic) reads each board. We check its reading against a gold set: boards read twice more, separately and with a stricter method, with every disagreement settled by looking at the image.

On a gold set of 141 boards (1,569 rows), our reading matched the supply name on 100.00% of rows, the board time on 100.00% and JW's status words on 99.87%. Both misses were a double space.
A second, separate reading of 244 boards from 2026 matched JW's status words on 99.81% of rows. Every difference was a space or a punctuation mark.
On 112 other boards, from 2025 and from later uploads, the second reading matched on 95.36%. Every miss was a cell with a colour and no words, where one reading copied JW's comment and the other left it empty. No word differed.
To check the steps, a separate reader was given only the plain meaning of each step and sorted 300 of JW's status texts. It put 285 of them on the same step as we did.

What JW's status words mean

JW writes its own words on each board. We put them on seven steps, best to worst, and keep two kinds of row apart from the steps.

Adequate: JW's board says the supply is supplying adequately or normally. On 2025 boards with no words, a green cell.
Fair: JW's board says the supply is supplying fairly. On 2025 boards, a yellow cell.
Poor pressure in places: JW's board says the supply is supplying, with poor pressure in some places or less pumping.
Low: JW's board says the level is low.
Warning: no water may occur: JW's board warns that poor pressure to no water may occur, or says the pumps are off without marking the row red. A warning, never counted as short of water.
Poor pressure to no water: JW's board says poor pressure to no water is happening or expected, or marks the pumps off in red.
Critically low: JW's board says the level is critically low. On 2025 boards, a red cell.
Scheduled overnight closure: JW's board says the outlet is closed on purpose, usually overnight, to build up storage. We count it apart, never as an outage.
Not on the scale: JW's words name no level we can place, such as a grey 2025 cell marked only "on bypass". We show the words and leave the day off the scale.

A day counts as short of water when JW's worst report for a supply that day was “poor pressure to no water” or “critically low”.

When the colour and the words disagree

JW colours each cell, and sometimes the colour says something else: “Critically low” in a blue cell, for example. On 1,197 of the 35,467 rows with words, the colour did not match the words. We go by the words. On 2025 boards with a colour and no words, we go by JW's own colour key, and the record marks those rows.

How the steps were set

We read each wording JW printed and placed it on the step for the worst level it names. A reason (“due to a power failure”) and a trend (“improving”) set nothing. A closure JW schedules to build up storage goes apart, never on the steps. Where JW prints poor pressure to no water only as a possibility (“may occur”), or says the pumps are off without marking the row red, the step is a warning: below no water, and never counted as short of water. The scale has a version, C3-v2, so any change to it shows in the data.

How a day is counted

A day's status for a supply is the worst status JW reported for it that day.
A status holds until JW's next board for that system, or for 36 hours, whichever comes first. After that the supply has no report until JW reports it again.
A day with no JW report is a gap. It stays in every count of days and is never counted as a normal day.
An outage is a stretch of time JW reported a supply at “poor pressure to no water” or “critically low”. An outage ends when JW first reports the supply better than “poor pressure to no water” or “critically low”. It has no reported end when JW's reports stopped before it ended, or when it was still going at JW's last report. We still count it, and its length is a minimum.
When JW reported a supply at “poor pressure to no water” or “critically low”, then there were up to 4 days with no board for it, then JW reported it at “poor pressure to no water” or “critically low” again, we count one outage, not two. We assume a Friday outage still there on Monday ran all weekend. Those days count in the outage's length, and its row says how many days had no board. They never count as days JW reported.
Stated against actual uses a stricter test: a supply has recovered when JW first reports it “supplying fairly” or better, and off bypass. It compares that time with the end time a JW notice gave.
A scheduled closure, usually overnight, is counted apart. It is never an outage.
When no JW board has reported a supply for 48 hours, its line says “No JW report since” that day. When JW has posted no board at all for 48 hours, every page says so at the top.

Gaps in the record

On these days there is no JW status board for any supply. Every chart draws them as gaps, and no count treats them as normal days.

25 July 2025 to 31 January 2026: 191 days.
10 February 2026 to 4 March 2026: 23 days.

There are also 28 shorter gaps, of 1 to 5 days.

Where a suburb's supply comes from

JW's reservoir pages and its supply table name the suburbs each reservoir or tower supplies. A suburb often appears under more than one and draws on all of them at once. We show every supply JW names. JW does not say which street each one reaches.

Where JW's lists use a formal name, such as Houghton Estate, the page uses the everyday name, Houghton, and gives JW's name beside the supply.

What the boards cannot tell you

This record holds what JW reported on its status boards and notices. It does not cover:

Your tap: The boards report reservoirs, towers and pump stations. Nobody reports taps.
Which street loses water first: Johannesburg Water warns of higher-lying areas but does not say which streets.
Pipe bursts: The boards do not report burst pipes or valve work in the streets.
Tankers: Where water tankers go, how many there are and what they cost are not on the boards.
Causes: Why a supply ran low is not on the boards. Where a JW notice gives a reason, we quote it as JW's.
Budgets: What JW or the City spends on water and repairs.
Targets: JW's or the City's targets for repairs, supply or leaks.

Questions people have asked in public, answered from this record, with what it cannot answer.

Why we republish JW's reports

JW posts the status of its reservoirs and towers as images on its website, one post at a time, and lists the suburbs each reservoir supplies. This site reads those posts, keeps them, and arranges them by suburb and by date, so anyone can see what JW reported and when.

We did not ask JW for permission. Every status here shows the time printed on the board and links to the post it came from. The post is the record. JW's access to information manual ↗ lists “water supply information (planned and unplanned interruptions)” among the records it makes available to anyone without a request. South African courts have held that copyright protects the words used to report the news, not the news itself (Moneyweb v Media24, 2016). The Constitution protects the right to receive and impart information.

We publish the facts we read: the supply, JW's words and the time. We do not show JW's board images. Each status links to JW's own copy. We keep a private copy of every board and notice JW posts, as evidence of what it said. We show our copy only when JW's own file is no longer online, labelled “Archived copy: JW's original is no longer online”, with the date it was last seen. So far every link goes to JW's own file.

Who makes this

Made by Phase Transitions (phasetransitions.ai ↗), a data science practice in Johannesburg. It is independent: it is not run by, or connected to, Johannesburg Water or the City of Johannesburg. The site is free and carries no advertising.

Each status links to JW's own post and image. Each figure names its data release. The whole record is a free download and an open API. This page states the rules we use to count, where JW's boards say nothing about counting.

Corrections

If we have read a board wrongly, or anything here is wrong, email graham@phasetransitions.ai with the page address. Johannesburg Water can write to the same address about anything here. We reply, usually within a few working days, and a fix appears in the next data release.

Privacy

JW's boards carry no personal information: they name reservoirs and towers, not people. This site keeps the words typed into its suburb search box, the time to the minute, and the number of results. It also counts page views by day: the page, whether the visit came from a search engine, another site or a bot, and the other site's name. It does not keep who typed or visited: no IP address, no cookie, no account.

Phase Transitions (Pty) Ltd is responsible for this site under the Protection of Personal Information Act (POPIA). Questions about privacy go to the same address. You can also complain to the Information Regulator ↗.