Accessible tables do not use colour or shading alone to convey meaning. For example, the use of green, yellow and red squares to show low-, medium- and high-risk categories will not be picked up by a screen reader, and colourblind or vision-impaired users may not be able to differentiate the colours:

You can still use colours as an aid for people who are not visually impaired, but you should also include a text element that conveys the same meaning – for example, by writing values in the cells and providing a code below the table:

Better still is to write what the colour means in each coloured cell:

Writing alt text for tables

Tables should be structured so that they can be accurately read by a screen reader. However, it can help your audience to also add alt text as a summary of the overall message or highlights of the table. They can then choose to read just the summary or to delve into the table for more detail:

Table of water use per industry in the Hunter region from 1990 to 2020. Across this period, the mining sector has consistently used the most water, and irrigated crops and viticulture have steadily increased their water use.

Alt text can also be used to help users navigate a complex table:

Schedule for regional mobile library services for June 2019. Towns are listed in the top row. 

Find the town closest to you in the top row, then read down that column to find out what dates the service will be in your town.

For more information, see Alternative (alt) text.