grey water: meaning, definition, pronunciation and examples
C1Technical / Formal / Environmental
Quick answer
What does “grey water” mean?
Wastewater from domestic activities such as bathing, washing dishes, or laundry, which is relatively clean and can potentially be reused for non-potable purposes like irrigation or toilet flushing.
Audio
Pronunciation
Definition
Meaning and Definition
Wastewater from domestic activities such as bathing, washing dishes, or laundry, which is relatively clean and can potentially be reused for non-potable purposes like irrigation or toilet flushing.
In broader environmental and technical contexts, it can also refer to any relatively uncontaminated wastewater not containing sewage (black water) or industrial waste, often managed as part of sustainable water resource systems.
Dialectal Variation
British vs American Usage
Differences
Primarily a spelling difference: 'grey water' in British English, 'gray water' in American English. The term and concept are identical.
Connotations
Neutral technical term in both varieties. Associated with environmental sustainability, water conservation, and eco-friendly building practices.
Frequency
Low frequency in general discourse but standard and expected in environmental science, plumbing, architecture, and sustainable development contexts in both regions.
Grammar
How to Use “grey water” in a Sentence
[N] is recycled for [purpose][N] from [source] can be used for [purpose]to treat/filter/divert [N]Vocabulary
Collocations
Examples
Examples of “grey water” in a Sentence
verb
British English
- The new housing development is designed to harvest and recycle greywater.
- We are considering grey-watering the allotment.
American English
- The community graywaters its public gardens.
- Some states have laws that graywater systems must be permitted.
adjective
British English
- They installed a grey-water tank.
- The grey-water recycling process is quite efficient.
American English
- The graywater infrastructure is still developing.
- We need a graywater-compatible detergent.
Usage
Meaning in Context
Business
In business, refers to systems, products, and services related to sustainable building and water conservation, e.g., 'The hotel installed a grey water recycling system to reduce its utility costs.'
Academic
Used in environmental science, engineering, and urban planning research, e.g., 'The study quantified the potential for grey water reuse in metropolitan areas.'
Everyday
Used by homeowners, gardeners, or in discussions about eco-friendly living, e.g., 'We use grey water from our washing machine to water the garden.'
Technical
A precise term in plumbing, sanitation, and environmental regulations, e.g., 'The building code specifies separate piping for grey water and black water systems.'
Vocabulary
Synonyms of “grey water”
Strong
Neutral
Weak
Vocabulary
Antonyms of “grey water”
Watch out
Common Mistakes When Using “grey water”
- Using 'grey water' to refer to any dirty or polluted water (e.g., industrial runoff).
- Confusing it with 'black water' (sewage).
- Treating it as a count noun (*'a grey water').
- Attempting to use it as a verb (*'to grey water the plants').
FAQ
Frequently Asked Questions
No, grey water is not potable (safe to drink). It requires treatment to remove soaps, grease, and skin particles before it can be reused, and even then, it is only used for non-potable purposes like irrigation or toilet flushing.
No, you should use biodegradable, plant-friendly soaps and detergents that are low in sodium, boron, and chlorine, as standard products can harm plants and soil if used for irrigation.
Common sources include bathroom sinks, showers, bathtubs, and washing machines. Water from kitchen sinks and dishwashers is sometimes excluded due to higher levels of grease and food particles.
Laws and regulations governing grey water reuse vary widely by country, state, and municipality. It is essential to check local building codes and public health regulations before installing a system.
Wastewater from domestic activities such as bathing, washing dishes, or laundry, which is relatively clean and can potentially be reused for non-potable purposes like irrigation or toilet flushing.
Grey water is usually technical / formal / environmental in register.
Grey water: in British English it is pronounced /ˌɡreɪ ˈwɔːtə/, and in American English it is pronounced /ˌɡreɪ ˈwɔːtɚ/ or /ˌɡreɪ ˈwɑːtɚ/. Tap the audio buttons above to hear it.
Phrases
Idioms & Phrases
- “There's a grey area in the regulations for grey water. (play on 'grey area')”
Learning
Memory Aids
Mnemonic
Think of 'grey' as the middle ground between 'white' (clean, potable water) and 'black' (sewage). Grey water is in-between — used but not fully contaminated.
Conceptual Metaphor
WATER IS A RESOURCE (to be conserved and cycled); WASTE IS A POTENTIAL INPUT (for a new cycle).
Practice
Quiz
What is the primary characteristic that distinguishes 'grey water' from 'black water'?