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Potable water is safe to drink but is not necessarily chemically pure. Freshwater treatment removes suspended material by filtration and reduces pathogens through sterilisation. Dissolved salts require other processes, such as distillation or reverse osmosis for desalination. These processes use energy and have different infrastructure needs. Choosing a source depends on availability, contamination and treatment requirements rather than assuming all clear water is safe.
Video by Cognito. The video’s own board label is retained; follow the specification reference and scope notes on this lesson for assessed content.
Viewing focus: Explain potable-water and wastewater treatment
After watching, attempt these questions before opening the answers. You can also use the written lesson below.
After watching 1: Does potable mean pure H2O only?
No. Safe water can contain dissolved minerals.
After watching 2: Which process removes dissolved salts by vaporising and condensing water?
Distillation. Salts remain while water vapour is condensed.
What you'll be able to do
Potable water is safe to drink but is not necessarily chemically pure. Freshwater treatment removes suspended material by filtration and reduces pathogens through sterilisation. Dissolved salts require other processes, such as distillation or reverse osmosis for desalination. These processes use energy and have different infrastructure needs. Choosing a source depends on availability, contamination and treatment requirements rather than assuming all clear water is safe.
Wastewater treatment separates large solids, allows sedimentation and uses biological treatment to reduce organic waste. It is not the same sequence as simply sterilising drinking water. Recycling metals can conserve ores and reduce extraction energy, while collection and sorting require resources. Glass, paper and polymers have different recycling constraints. A material’s usefulness, lifetime and contamination affect whether reuse or recycling is practical.
A lifecycle assessment considers raw-material extraction, manufacture, use and disposal. Numerical results depend on the chosen boundaries and data quality, while some effects are difficult to quantify. Sustainable development meets present needs while preserving future opportunities. In industrial chemistry, improve atom economy, energy efficiency and feedstock choice as well as product yield. Fertiliser manufacture connects ammonia from the Haber process with acids and mined minerals; benefits to crop growth should be weighed against resource use and environmental losses.
Attempt these problems on paper before opening the worked reasoning. Explain your steps as well as giving a final answer.
Common mistakes to avoid
Key takeaways
Question 1: Why can a reusable container have a higher manufacturing footprint yet lower impact per use?
Compare impact per equivalent service over its lifetime.
Check the assessed scope and practical or mathematical requirements.
An external explanation or interactive activity to use alongside the lesson. It may include extension material.
Close the notes and answer from memory. Revisit any explanation you cannot yet reconstruct.
Test yourself
Answer a few questions, then review anything you missed.
Start with the quiz above to check the key ideas. You can also choose another topic from the practice library.