How can buildings save water and manage rainwater sustainably?
Water conservation and management in buildings: saving water, rainwater harvesting and greywater reuse, and managing surface water with SUDS.
A CCEA GCSE Construction answer on water conservation and management in sustainable buildings: ways to save water, rainwater harvesting and greywater reuse, and managing surface water with sustainable drainage systems (SUDS).
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What this dot point is asking
CCEA wants you to explain how buildings can conserve water and manage rainwater sustainably: ways to use less water, how rainwater harvesting and greywater reuse work, and how sustainable drainage systems (SUDS) manage the rain that falls on a site. Clean water takes energy to treat and supply, so saving it is part of building sustainably.
The answer
Why water matters
Treated mains water takes energy to clean and pump, and demand for it keeps rising, so wasting it is wasteful of both water and energy. At the same time, hard surfaces like roofs and paving stop rain soaking into the ground, which can cause flooding and overload drains. Sustainable construction therefore both saves water inside the building and manages rainwater on the site.
Saving water
Rainwater harvesting
This cuts the amount of mains water used and reduces the rain running off the site at once.
Greywater reuse
Greywater is the lightly used water from baths, showers and basins (not from toilets or kitchens). After simple treatment it can be reused for flushing toilets or watering the garden, saving mains water for jobs that need it.
Managing surface water with SUDS
SUDS reduce the risk of flooding, ease the load on the drainage and sewer system, and can clean the water and create habitats, all of which support sustainability.
Worked example: a water strategy for a new house
Examples in context
- Example 1. A dual-flush toilet
- An old toilet might use a large flush every time, while a dual-flush toilet offers a smaller flush for most uses, cutting the water used for one of the biggest household uses without any loss of function.
- Example 2. A water butt on the downpipe
- A simple water butt collects roof rainwater for the garden, saving treated mains water during dry spells and reducing the rain rushing into the drain during a downpour, a small-scale example of rainwater harvesting and SUDS together.
- Example 3. A permeable car park
- Replacing solid tarmac with permeable paving lets rain soak through into the ground instead of running off into the drains, reducing the risk of flooding downstream, which is the core idea of SUDS.
Water conservation completes the picture of sustainable construction in Unit 2. Alongside reducing the wider environmental impact, improving energy efficiency, and generating renewable energy, managing water carefully helps a building tread more lightly on the planet across its whole life.
Try this
Q1. Name one water-efficient fitting that reduces the water used in a house. [1 mark]
- Cue. For example a dual-flush toilet, a spray tap or a water-saving shower head.
Q2. Give two suitable uses for harvested rainwater. [2 marks]
- Cue. For example flushing toilets and watering the garden (non-drinking uses).
Q3. State one benefit of a sustainable drainage system (SUDS). [1 mark]
- Cue. It reduces flooding by slowing and soaking away rainwater (and eases the load on the drains).
Exam-style practice questions
Practice questions written in the style of CCEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
CCEA style4 marksDescribe two ways the amount of water used in a house can be reduced.Show worked answer →
Any two clear water-saving methods, each described:
- Fit water-efficient fittings such as low-flush (dual-flush) toilets, spray taps and water-saving shower heads that use less water for the same job.
- Collect and reuse rainwater (rainwater harvesting) for jobs that do not need drinking-quality water, such as flushing toilets and watering the garden.
Other acceptable points include reusing greywater from baths and basins, fixing leaks and dripping taps promptly, and metering water so users are aware of how much they use.
Markers reward one mark for naming each method and one mark for describing how it saves water.
CCEA style4 marksExplain what rainwater harvesting is and give two uses for the collected water in a house.Show worked answer →
Rainwater harvesting is collecting rainwater (usually from the roof, through the gutters and downpipes) and storing it in a tank or butt so it can be reused instead of running to the drain.
Two suitable uses, because the water is not of drinking quality: flushing toilets, watering the garden, washing the car, or feeding a washing machine. Drinking and cooking still use mains water.
Markers reward a correct description of collecting and storing rainwater (two marks) and two valid non-potable uses (one mark each).
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