Saturday, 18 March 2017

Domestic Rainwater-Harvesting

I guess 652, 300 litres of water falls on my parents roof per year on average.

1,787 litres per day.

(1100mm per year on average. Our roof area might be around 593m2. So, 652.3m3 rainwater per year.)

Our daily consumption of town-water averaged about 454 litres. That rose to 795 litres per day in summer when I was watering the lawns - and in addition to that I've been pumping water out of the ground.

But still, 1,787 litres per day of rainwater would be plenty - if we were storing it.

To store that amount of water at once, if the whole of our roofed area had underground tanks under the house - the tanks would only need to be about 1.1metres deep, I guess.

But you wouldn't need to store all the water at once: because it doesn't rain only once a year.

New houses could have water-storage spaces built into the external walls of the house. That would double as insulation, and sound-proofing.

Or external fences and walls could be made out of water-storage containers.

Or spaces under decking.

Electric water-pumps might cost around 30cents per hour to operate, guessing.

You might need some sort of water-purification system.

Grey water could also be stored. Ordinary dishwashing liquid is okay for lawns - it acts like a soil-wetting agent, softens the soil and water, allows more water and nutrients to be drawn up into the plant.

You could eventually recover the costs of installing the water-harvesting system from savings off your water-consumption bills.

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