Is rainwater harvesting a thing in a city environment?

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RichInSpirit

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This was running through my mind during the recent dry weather spot.
With water shortages and hose pipe bans keeping your plants alive and even washing your car can become criminal activities.

This video from the UK came up on my feed this morning for a cheap DIY system. https://youtu.be/MY8J8n6enmE?is=exfgaMp80vB66eT5

I would think space in back gardens is pretty limited in the city but maybe I am wrong.
 
RichInSpirit said:
I would think space in back gardens is pretty limited in the city but maybe I am wrong.
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Smaller spaces usually have less planting that requires watering. A medium sized plant in a 40cm pot requires ~2l of water a week, thirsty plants like bushes or hedging need about 25l per sqm a week, so a compact water butt may last longer than you think.
 
When we had the water charges in Ireland for a brief period about 10 years ago, I was renovating my house and looking into using rainwater for flushing toilets, the outside tap, etc. The cost of an underground water storage tank, the filters, pumps, additional header tank in the attic, additional pipes and controls to have your toilets flushed with rainwater was huge. You'd never get back the initial investment. The biggest cost by far was the underground tank in the garden, the pump and the controls. The additional pipes internally weren't huge so I actually put them in and I could switch to using rainwater for toilets if required but can't ever see it happening.
Even in commercial projects where you could have a Multinational HQ and they want to be seen as green, they're looking at everything but not using rainwater for toilets, etc.

On a smaller scale, a water butt tank in the garden for watering a few plants in a dry spell is very affordable. You can even get a small pump connected to a water butt tank which is connected to a hose making watering the garden very easy.
 
I have a large water butt attached to gutter, can be used for watering plants when needed or at a push I could bring in buckets of water to flush toilets if dire necessity! I used it during the hosepipe ban for potted plants.
 
Duddaa said:
The cost of an underground water storage tank, the filters, pumps, additional header tank in the attic, additional pipes and controls to have your toilets flushed with rainwater was huge.
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A complete system to supply grey water needs costs around €3k + installation now. Supplying potable water will mean additional parts and maintenance costs for the enhanced filtration required.
 
We are building and using these is a condition of planning https://www.dublincity.ie/sites/default/files/2021-04/a-how-to-guide-to-rainwater-planters-english.pdf

The rain travels through the planters down into the garden and dispersed through pipes under the lawn.
 
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Most domestic rainwater harvesting systems work by capturing the runoff from the roof and, the smaller the area of your roof, the less runoff there will be. Urban houses tend to have smaller footprints than rural houses, and multistory houses in particular have much less roof area per occupant than single-story houses. So there is perhaps less scope for rainwater harvesting in urban areas than in rural areas.

But, as others have pointed out, it may still make sense, since urban properties generally have less planting that require irrigation. So a relatively modest harvesting system may still make a useful contribution.
 
Of course, it has to rain to make it worthwhile - even a large butt will only last so long
 
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