The Desolenator: producing clean water: reading answers and analysis
Inspired by Thai rooftop solar heaters, William Janssen built the Desolenator: a portable, wheeled, solar-powered unit that turns sea, river or rain water into 15 litres of drinking water a day. With water stress spreading and desalination plants too costly for many countries, it's aimed at poor households (via microfinance) and niche Western users, as a social venture rather than a profit machine.
Questions 14-26 · 13 marks · 2 question blocks
Where the answers sit
The headings (14-20) take one section each, A to G, and three of the ten headings are left over. The summary (21-26) is all in C.
Questions 14-20
Follow the logic of each section. A goes from idea to product, B covers the many water sources, and C explains what makes the device different (sunlight only). D gives the scale of water shortage, E the range of customers, and F says profit isn't the main goal. G covers funding raised so far. The unused headings (an unexpected benefit, production problems, a warm welcome) describe nothing in the text.
| Question | Answer | Also accepted |
|---|---|---|
| 14 | iii | — |
| 15 | vi | — |
| 16 | v | — |
| 17 | x | — |
| 18 | iv | — |
| 19 | viii | — |
| 20 | i | — |
Questions 21-26
C walks through the device in order: what makes it portable, the thin layer water forms over the panel, what traps particles, what comes out of the second tube, what the screen shows, and what the company provides when needed. All six are nouns taken directly from C.
| Question | Answer | Also accepted |
|---|---|---|
| 21 | wheels | — |
| 22 | film | — |
| 23 | filter | — |
| 24 | waste | — |
| 25 | performance | — |
| 26 | servicing | — |
The questions most people get wrong
v. C's 'main selling point' is that it needs no generated power supply, only sunlight, which is what sets it apart from alternatives. It isn't about the range of water sources (B).
viii. 'A venture with a social mission' comes first, with the bottom line mentioned second, so profit isn't the primary goal.
Water flows 'as a thin film' between the glazing and the panel, so the answer is 'film'.
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The full Cambridge 15 Test 3 reading paper: all three passages, 60 minutes, marked the second you finish with a review of every answer. Already done it? Take it again and see if the same traps still get you.
Cambridge IELTS 15, Test 3, Reading Passage 2. The passage name belongs to Cambridge University Press. No passage text or question wording is reproduced on this page. The answers are published for self-marking, and the analysis is our own.