Showering, cleaning, drinking, flushing, and washing clothes all use water. A lot of water! As the climate changes and populations increase, supply is struggling to keep up with demand. Making our city’s buildings more sustainable conserves vital drops. But what exactly can we do to make our water use more efficient?
Fabric-first retrofits are elegant fixes for energy efficiency, but in developed nations at least, water is not so common on the agenda. Possibly because it doesn’t pose such an immediate contribution to carbon creation, even if heating water does contribute to fossil fuel depletion. Even so, water is a resource we shouldn’t take for granted. Those of us who have more of it should use it responsibly. We’ve put together this guide to show you how.
These are chiefly steps you can take to amplify the impact of shallow retrofits, but small adjustments to everyday behaviour count for a lot: they are easy to master and quick to provide rewards in terms of water and money saved.
The effects of climate change don’t only mean desertification and drought. Erratic precipitation patterns are bringing more floods to our populated regions.
Stormwater runoff enters drainage systems and sewers from, or forms pools on, impermeable materials abundant in cities, such as concrete. Too much rain leads to (flash) flooding. Living roof retrofits stem the flow by catching some of the water and reduce the chances of disaster.
We can make use of this non-potable water. It can be channelled to feed toilet cisterns or even be used for washing and laundry. Add a water butt for further rainwater harvesting to supply plants and vegetables and save yourself the cost of all that tap water.
Consult professionals before proceeding with greening. All that wet soil is a heavy load; be sure your build can sustain it. A&P Lofts in Atlanta, USA was an abandoned historic building that required steel reinforcement before adding a living roof – but it worked. Include adequate waterproofing to spare the property from damage. And incorporate drainage to stop the roof from getting waterlogged. Drainage holds water that feeds vegetation, too. There are plenty of readymade waterproof drainage insulating units available on the market.
For flimsier rooftops, (re)movable modular roofing – essentially broad, flat plant pots – provides the benefit of water storage and filtering, although with less insulating properties.
Extracting Wet from Dry
In dry regions, water efficiency is the only option. “Currently, arid environments cover over 30% of the world’s land surface”, and it’s growing, writes Arup in their Cities Alive report. “These regions face complex challenges such as water scarcity” with “rapidly growing populations” exacerbating water stress.
Rooftop dew harvesting in the Atacama Desert, Chile, and in Lima, Peru, allows households to extract precipitation from condensing atmospheric fog that rolls in from the ocean. In some areas, a 15 sq/ft net (1.4 m2) captures and channels enough for an individual’s daily needs – about 40 litres. Some towns cannot rely on this source because of evaporation through heat and wind, but it’s a reasonable top-up.
In Morocco, this method has slowed the rate of rural-to-urban migration; formerly, people were chasing the water supply, and infrastructure meant it favoured urban centres. Slowing this population boom also helps water management in dense urban locations and allows cities to catch up and plan for rising demand.
Rains and Drains
On the German-language website Brand Eins, Florian Boer, a Dutch expert in urban research, design, and landscaping, said the usual engineering solution to too much precipitation falling in cities would be to build bigger sewers, floodwalls, and rainwater retention basins: all big, costly, disruptive projects.
Benthemplein, a square in Boer’s hometown of Rotterdam, has undergone a makeover. It’s now a floodable ‘water square’: a space of public value consisting of pits that double-up as a water repository in times of heavy rainfall. This Dutch example provides an area for recreational sport and performances complete with amphitheatre-style seating in dry weather or a temporary reservoir at other times, from where the water can be redistributed safely. Up to 1.7 million litres of it!
Wastewater pipes from surrounding rooftops were “disconnected from the Rotterdam sewage system”, reports C40, and redirected to the square – showing how revitalisation of public spaces and retrofitting can coordinate.
Save the Swales
On a ground level, sustainable drainage systems protect properties from excess stormwater. Swales are wide, shallow ditches that collect rainwater rather than letting it sit on pathways or saturate the soil. They’re often seen in cities running alongside pavements and driveways. Populated with plants and grasses, they are robust, look natural, and filter water. They slowly release it into the water table rather than draining it straight into the sewer.
Consider Your Appliances
Block the Loo
Approximately 30% of household water use is attributed to flushing the toilet. Some older lavatories use up to 13 litres of clean water every flush, although the average is still an eye-popping nine. Modern latrines are more efficient, and often provide duel flush buttons or time-release handles that allow the user to choose the quantity to suit the payload.
Adding a cistern displacement device – effectively a block that fills part of the water storage unit – reduces the amount of water kept in wait and therefore used to flush. This can be done on the cheap, with a water-filled plastic bottle.
As seen in our deep retrofit example from Manchester, a toilet with an integrated hand basin is a real H2O saver. Water from hand-washing part-fills the cistern, so it gets reused in flushing. This also saves a little space. Although probably not big enough for washing your face, it’s good for small rooms where the toilet is separate from the bathroom.
Keep Your Head – A Better Shower Experience
Harvard University claims the average shower lasts 8 minutes, using 20 US gallons (75 litres) of water. They recommend sticking to 5 minutes. Upgrading to a low-flow showerhead as well is worthwhile, saving up to 60% of water.
Choose right for your environment. For less steam, opt for laminar flow – classic streams of water. In damper climates, this will create less humidity than ‘misty’ aerating showerheads, so lessens chances of health-damaging mould forming.
Don’t automatically dismiss the bath, either. Experiment. Plug the tub and shower as normal. Record how long you washed and how high the water level gets. Another time, run the bath at the same pressure for the same length of time. If you can’t bathe in that level, stick to the shower – it’s using less for the same cleansed feeling.
Go one step further: stand over a bucket to collect wastewater. Greywater recycling reduces water demand and the amount entering drainage and sewage systems, minimising flooding and infrastructure impact.
Even with soap traces, greywater can be used for irrigation if done responsibly. New Mexico State University offers an easy-to-follow guide. A good budget tip: when distributing the water over plants and vegetable garden, filter it through a cloth bag to remove impurities.
Living Off Air and Water
Save up to 40 litres of water each day by fitting an aerator to your kitchen tap. It maintains the same sense of pressure and benefits for washing using less of the wet resource.
According to the USA’s Environmental Protection Agency, “household leaks can waste nearly 1 trillion gallons of water annually nationwide” with 10% of homes wasting “90 gallons or more per day” this way. Burst pipes around the home can spell disaster. Water damage can arise from breaches in supply to toilets (11 litres a minute), the fridge (3.7 litres every minute), and washing machine (45.5 litres every 60 seconds). Considering the average flush uses a comparable 8 litres and wash cycle 45 litres, this signals gross inefficiency!
It’s not just a household problem. “Asia loses around 29 billion cubic metres of urban treated water every year, valued at nine billion dollars annually”, writes The New Humanitarian. In England and Wales, underground pipes lose enough water each day to fill 1,180 Olympic-sized swimming pools (3 billion litres). While in Japan, up to 35% of potable water is seeping out of cracked, aging pipes and when undetected results in a loss of 4,500 cubic metres in just 6 months.
As the UN’s World Water Development Report 2021 found that “1.6 billion people face ‘economic’ water scarcity” (they lack the means to access it) and “four billion people will be living in water-stressed areas” by 2050, we need to conserve every drop and take action to prevent waste in the future.
City administrations have a few options for infrastructure efficiency:
- Reducing pressure during low-demand periods – at least it curbs the loss while the leak is dealt with.
- Require water companies to set in place leak reduction plans, as has been introduced in the UK.
- Charge for water use by volume – in some EU countries where water is still a free resource, consumption is patently higher.
In individual buildings, we can also make changes:
- Add lagging to pipes to prevent bursts from freezing.
- Replace old copper pipes before they rust and holes form. Newer materials are less susceptible to corrosion or damage from water flow and natural acidity.
- Take a plunger to plugholes! Dirt, grime, and food particles can block flow. A regular clean also avoid some nasty smells from building up.
- Keep your outside guttering clean, too. It keeps water flowing where it should, rather than down walls, which can cause internal damp.
Put the Kettle On
Kettles are about 40% more efficient than boiling on the hob but are developing to use more energy to sate our desire for hot water quicker. The problem really lies in us heating more than we need. A waste of energy and water. Boil only what you need by measuring amounts before hitting the ‘on’ switch.
Still got some leftover? Wait for it to cool then use it for washing up or watering the plants.
Make a Clean Break
Turn off the tap. Simple. Letting the liquid flow while cleaning your teeth is a waste. A 200 gallons (750 litres) a month waste! And do the same when washing your face, lathering your hair (be it head or legs), or shaving.
Don’t Bottle It!
There’s a stigma attached to recycled water. We don’t like the thought of bathing in or drinking anything that we think is contaminated, even after it’s treated.
Arup suggests “awareness campaigns”, which “reframe this difficult issue in a more positive light to win people’s support”. We need to move fast, as the supply is already becoming part of our cityscape. You might like our guide to changing behaviour to find out how.
It does work. Melbourne in Australia treats and reclaims almost 12 million gallons (25 million litres) of pre-used water each day. It’s suitable for irrigation, which constitutes almost 50% of all residential water use in the city, saving masses on potable supply. Florida’s Groundwater Replenishment Project, following rigorous tests, has proven to be of better quality than bottled water.
Retrofit to Manage Water – in a Nutshell
There’s plenty to be done to conserve our most valuable resource as usable water resources become more and more stretched. Thoughtful city planning, incorporating the resistant qualities provided by nature, changing our mindset, and careful consideration for how we live our lives will all play a part in ensuring the environmental and social stability we desire can be achieved through sound management and efficient water use.
,  Cindrić, H. (2018). Cities Alive: Rethinking Cities in Arid Environments. Arup. https://www.arup.com/perspectives/publications/research/section/cities-alive-cities-in-arid-environments